Contents Contents Creating a Simulation Example: A Dipole Antenna AMDS User s Guide

Contents Contents 1 Creating a Simulation 7 Introduction 8 Data Files for Examples 8 Software Organization 9 Constructing the Geometry 10 Creating the Mesh 11 Defining Run Parameters 13 Requesting Results 15 2 Example: A Dipole Antenna 17 Starting AMDS 19 Constructing Geometry 20 Creating the Mesh 22 Choosing Cell Size 22 Meshing 23 Saving the Geometry 24 Defining Run Parameters 25 Defining the Location of the Port 26 Defining the Waveform 28 Requesting Results 30 Field Snapshot Sequence 30 Saving the FDTD Project 32 Running the Analysis 33 Examining the Results 35 View Field Sequence 35 Exporting the Animation to an MPEG File 40 AMDS User s Guide 1

Contents Plotting 42 Frequency Domain Results 45 Steady State Analysis 47 3 Example: A Low Pass Filter 55 Modeling the Geometry 57 The Substrate 57 The Strip Line 61 Generating the Mesh 68 Adding the Wire Feeds 71 Adding a PEC Boundary Condition to Model the Ground Plane 76 Adding the Source and Load Ports 77 Specifying the Input Waveform 79 Field Snapshot Sequence 80 Running the Analysis 81 Examining the Results 82 Example: Adding Calibration to the Low Pass Filter 89 Pre-processing 89 Adding the calibration 90 Running the Simulation 104 Examining the results 106 4 Example: A Patch Antenna 109 Constructing the Geometry 111 Materials 111 Substrate Geometry 112 Patch Geometry 114 Creating the Mesh 122 Choosing Cell Size 122 2 AMDS User s Guide

Contents Adaptive Meshing 123 Creation of Feed Line and Port 129 Run Parameters 134 Setting the Outer Boundaries of the Model 134 Define the Waveform 135 Requesting Results 136 Field Snapshots 136 Running the Analysis 137 Examining the Results 138 View Field Snapshot Sequence 138 Plotting 141 Example: Adding Calibration to the Patch Antenna 146 Constructing the Geometry 146 Generating the mesh 151 Adding the Feed and Calibration 153 Running the Simulation 163 Examining the results 164 5 Example: A Pyramidal Horn 169 Constructing the Geometry 171 Defining the Horn and Feed 171 Changing the Horn Material 174 Creating the Mesh 177 Selecting a Suitable Cell Size 177 Defining Run Parameters 179 Specifying the Input Voltage 179 Specifying the Voltage Waveform 181 Requesting Results 183 Specifying Near Field Points 183 AMDS User s Guide 3

Contents Specifying a Field Snapshot Sequence 184 Running the Analysis 186 Examining the Results 187 Checking for Convergence 187 View Field Snapshot Sequence 189 Calculate and View the Far Field Pattern 190 6 Static Analysis 197 Constructing the Geometry 198 Creating the Mesh 204 Defining the Static Voltages 208 Defining the Requested Output 210 Running the Analysis 212 Examining the Results 213 View Single Transient Field 213 7 Example: A Monopole Antenna on a Conducting Box 215 Introduction 217 Constructing the Monopole Antenna 218 Running the Analysis 224 Examining the Results 225 8 Example: A Thin Dipole Antenna 229 Introduction 231 Constructing the Geometry 233 Defining Run Parameters 238 Requesting Results 241 Running the Analysis 242 4 AMDS User s Guide

Contents Examining the Results 243 9 Example: SAR Calculations 247 Validation of Specific Absorption Rate (SAR) Calculation in AMDS 248 10 Example: Calculating Antenna Diversity Parameters 257 Importing the Geometry, Hierarchy and Materials 259 Meshing the Geometry 267 Creation of the Feeds 274 Setting the Waveform 276 Running the simulation with Monopole 1 active 278 Running the simulation with Monopole 2 active 280 Calculating the Antenna Diversity Parameters 282 11 Example: Evaluating the Hearing Aid Compatibility 287 Introduction 288 Importing the geometry, hierarchy and materials 290 Placement of the HAC Scan Area 296 Meshing the Geometry 300 Creation of the Feeds 302 Setting the Waveform 307 Running the Simulation 309 Evaluating the HAC 310 Viewing the Fields on the HAC Scan Area 315 12 Additional Examples 319 Example: The Ferrite Circulator 320 AMDS User s Guide 5

Contents Example: The Folded Slot Antenna 323 Example: Finger Lange Coupler 325 Example: The Meander Line 327 Example: Coplanar Stripline Bandstop Filter 331 Example: Wilkinson Power Divider 333 Example: Drude Model of Plasma Sphere 337 Example: A Calibrated Microstrip-fed Dipole Antenna 340 Creating the Geometry 341 Generating the Mesh 350 Adding the Feed and Calibration 351 General Comments on the Calibration 362 Specifying the Waveform 365 Running the Simulation 367 Examining the Results 368 13 3D CAD Import Example - The Helicopter 371 Importing the CAD File 372 Creating the FDTD Mesh 375 A Numbered References 377 References 378 Index 379 6 AMDS User s Guide

Agilent W2100 Antenna Modeling Design System User s Guide 1 Creating a Simulation Introduction 8 Software Organization 9 Constructing the Geometry 10 Creating the Mesh 11 Defining Run Parameters 13 Requesting Results 15 Agilent Technologies 7

1 Creating a Simulation Introduction This manual is designed to assist new users in learning how to utilize the Agilent Technologies Antenna Modeling Design System (AMDS) and describe some of the advanced features available for experienced users. Following an overview of AMDS, the first series of examples provide simple applications that will illustrate how to create models easily and efficiently, as well as run analyses and investigate results. Additional examples, described later in this manual, illustrate the range of advanced features available in AMDS. Data Files for Examples The Agilent EEsof Knowledge Center provides access for downloading and installing the AMDS example data files. For more information, refer to the Software Downloads section of the Agilent EEsof Knowledge Center at: http://www.agilent.com/find/eesof-knowledgecenter/ Use the following information to download the AMDS example.dat files. 1 Go to the Agilent EEsof EDA Web site and click the link to the Knowledge Center, or simply follow the URL above. 2 From the EEsof Knowledge Center, click the AMDS link in the Software Downloads section. 3 Click the appropriate AMDS link for the version desired. 4 Click the Download Examples link and follow the instructions provided. 8 AMDS User s Guide

Creating a Simulation 1 Software Organization Creating a simulation in AMDS consists of the following four steps: 1 Constructing the geometry 2 Creating the mesh 3 Defining run parameters 4 Requesting results A project is developed by moving through these steps. This is reflected in the sequence of the tabs displayed in the software as shown in Figure 1. The first tab on the left, Summary, provides an overview of the current project status and settings, as parameters and requested results are entered. Figure 1 The Main Tabs AMDS User s Guide 9

1 Creating a Simulation Constructing the Geometry AMDS uses solid, dimension-based modeling to create geometries. To model a geometry, you can use the library objects and editing functions provided, or you can import CAD files from 3rd party solid modeling packages. Figure 2 Geometric Modeling 10 AMDS User s Guide

Creating a Simulation 1 Creating the Mesh Once a geometry is defined, it must be discretized into Finite Difference Time Domain (FDTD) cells. This process is called meshing and the mesh tab is displayed below in Figure 3. Figure 3 The Mesh Tab To create a mesh, the required cell sizes must be determined. There are several factors to be considered when determining cell size. Wavelength: The primary constraint on cell size is wavelength. The FDTD cell can be no larger than 1/10 of the smallest wavelength used to excite the model. Hence the maximum cell size can be determined from c L max = -------------- 10 f AMDS User s Guide 11

1 Creating a Simulation Where: L max is the maximum cell dimension c is the speed of light, 3x10 8 m/s in free space f is the frequency of excitation (Hz) If materials other than good conductors are included in the calculation the velocity of light will be reduced in those materials and the FDTD cell size must be reduced accordingly. Geometry features: The FDTD cell can be no larger than the smallest feature of your geometry so that the object can be represented accurately. For example, if the geometry contains two wires and the distance between them is smaller than the maximum cell size, a smaller cell size is needed. Accuracy: Smaller cell sizes result in greater accuracy in the simulation. 12 AMDS User s Guide

Creating a Simulation 1 Defining Run Parameters Once the mesh is defined, a stimulus or excitation is needed to drive the calculation. The waveform tab is shown below in Figure 4. Figure 4 The Waveform Tab There are several pre-defined waveforms, or a user defined waveform can be provided. Source types of plane wave, discrete voltage and/or current sources, and Gaussian beams AMDS User s Guide 13

1 Creating a Simulation are supported. It is necessary to specify how the calculation treats the boundaries of the problem space by specifying the outer radiation boundary conditions. 14 AMDS User s Guide

Creating a Simulation 1 Requesting Results In order to run the simulation, output data must be requested. Many different types of output are available. Agilent Technologies uses an open file format, so that output files can be used with third-party or in-house software. The most commonly used output files are described in the AMDS Reference Manual. Figure 5 The Save Steady-State Data Tab AMDS User s Guide 15

1 Creating a Simulation After performing these steps and saving the geometry and project files to disk, an FDTD calculation can be performed using the Results > Run Calculation tab. When the calculation is complete, output data is available from the Results tab and the Geometry > View tab. 16 AMDS User s Guide

Agilent W2100 Antenna Modeling Design System User s Guide 2 Example: A Dipole Antenna Starting AMDS 19 Constructing Geometry 20 Creating the Mesh 22 Defining Run Parameters 25 Requesting Results 30 Saving the FDTD Project 32 Running the Analysis 33 Examining the Results 35 Agilent Technologies 17

2 Example: A Dipole Antenna This is a simple dipole antenna example using a length of 30 cm so that the dipole will be one wavelength long at 1 GHz. This means the frequency in GHz will correspond to the dipole length in wavelengths. In this example, the input frequency will be 0.47 GHz. The result is a dipole that is 0.47 wavelengths long. The dipole will be built of perfect electrically conducting (PEC) material. Similar results would be obtained if the dipole were constructed of highly conductive material such as copper. Data files for AMDS examples are available from the Agilent EEsof EDA Web site. For more information on downloading the example data file(s), refer to Data Files for Examples on page 8. 18 AMDS User s Guide

Example: A Dipole Antenna 2 Starting AMDS When AMDS starts, the Summary tab is displayed, as shown in Figure 6. This tab includes a brief overview of the project properties. At this point, the dipole project has not started, so this tab contains no data. Figure 6 The Summary Tab AMDS User s Guide 19

2 Example: A Dipole Antenna Constructing Geometry To begin creating the dipole geometry, 1 Click the Geometry tab. By default, the Geometry > View will be the active window. 2 Click the Wire button on the Geometry > View toolbar. The Wire dialog box is displayed as shown in Figure 7. Figure 7 The Wire Dialog Box 3 Select Centimeters for the Units, and set the wire dimensions from 0 to 30 in the x direction. 4 The material selector in the Geometry > View tab is initially set to PEC (perfect electrical conductor), as shown in Figure 8. 20 AMDS User s Guide

Example: A Dipole Antenna 2 Figure 8 The Material Selection Menu 5 This is the same material shown in the Wire dialog box. PEC is used for the dipole, so simply click the Add button followed by the Close button in the Wire dialog box. The geometry is created. AMDS User s Guide 21

2 Example: A Dipole Antenna Creating the Mesh After constructing the geometry, click the Mesh tab (secondary tab) under the Geometry tab to begin creating the mesh. The Mesh tab is shown in Figure 9 on page 23. Choosing Cell Size The source of the feed to the dipole should be placed at the center point along its length, at 15 cm. Because the source will occupy one cell edge, choose a cell size that will result in the dipole length being an odd number of cells. This is a small problem space, so choose a cell size such that the dipole will be 51 cells long. 30 cm / 51 cells = 0.588 cm/cell This cell size is significantly smaller than the maximum allowable cell size (one tenth of the shortest wavelength), found using the equation: L max = c -------------- 10 f 3 10 8 L max = -------------------------------------- 10 0.47 10 9 = 6.38 cm cell In Figure 9 below, the FDTD space is indicated in blue. The green region inside is the bounding box of the geometry. 22 AMDS User s Guide

Example: A Dipole Antenna 2 Figure 9 The Mesh Tab Meshing Enter the information in the box on the left labeled New Mesh Parameters. 1 Select Centimeters as the Grid Units. 2 Set the cell size as 0.588 cm in each direction. 3 Click the lock icon to save this setting. 4 Set the uniform padding at 25 cells. 5 Click the Generate Mesh button. AMDS User s Guide 23

2 Example: A Dipole Antenna To view the grid, 1 Return to Geometry > View tab. Be sure that the mode selector is set on Mesh Mode. 2 Along the right edge of the window is a column of buttons. Click the Grid button (the first one). Saving the Geometry To save your geometry, click the Save Geometry button on the main toolbar. Note that the icon has a small FDTD cell in the corner to distinguish it from the Save Project icon. With the geometry defined and meshed, the stimulus will be introduced and the type of output data specified. 24 AMDS User s Guide

Example: A Dipole Antenna 2 Defining Run Parameters To define your run parameters, 1 Start this process in the Geometry > View window, Mesh Mode. 2 Set the slice number to 26. For this simulation, a voltage source will be used in series with a lumped 50Ω resistor located at the center of the dipole. Figure 10 Mesh Mode View with Measuring Tool AMDS User s Guide 25

2 Example: A Dipole Antenna Defining the Location of the Port To define the location of the port, 1 Select the Grid button so that the cells are displayed. 2 Zoom in using one of the available methods, for example, the dynamic zoom. 3 AMDS provides an icon for placing ports and components. Select the ports and components icon and move the cursor such that the marker is located on the wire at the center of the dipole location (52, 26, 26) along the wire. 4 Right-click at this location and select the Add default feed option. As an alternative, a measuring tool helps you to place objects. Press the middle mouse button at the location from which you want to measure and drag the mouse. The default feed will be used in this example, but it is good practice to review the feed settings. To do this, 1 Right-click on the feed and select Edit. The Components/Ports tab is displayed. 2 Ensure that the x, y, and z locations on the left side of the window are correct and that X-Directed is showing, as shown in Figure 11. Also ensure that S-Parameters/VSWR Calculation is turned On. 26 AMDS User s Guide

Example: A Dipole Antenna 2 Figure 11 Components/Ports Tab 3 Notice that Port is checked. This means that this feed will be considered a port, which will cause voltage and current data to be saved at this location. If you return to Geometry > View, you should see the source location indicated in green, as shown in Figure 12. Deselect the icon. AMDS User s Guide 27

2 Example: A Dipole Antenna Figure 12 Source location Defining the Waveform To define the waveform, 1 Choose Run Parameters > Waveform and set the following as shown in Figure 13. Waveform Type: Sinusoid Waveform Frequency (GHz): 0.47 Convergence Threshold (db): -30 28 AMDS User s Guide

Example: A Dipole Antenna 2 Figure 13 Waveform Tab AMDS User s Guide 29

2 Example: A Dipole Antenna Requesting Results After defining the run parameters, you can request results. Field Snapshot Sequence A transient field sequence is a collection of transient fields that can be displayed as an animation (or movie). Each field exists at the same slice and plane in the mesh, but occurs at a different point in time. Clicking on Save Field Snapshots saves the E, H, J, and S values for each cell in the slice and plane. To add a transient field sequence to the requested output, 1 Return to the Geometry > View window. 2 Right-click anywhere in the plane of the dipole. 3 From the pop-up menu, choose Save Data > Field Snapshots. The Save Field Snapshots tab is displayed and the values for the plane selected can be specified as shown in Figure 14. 30 AMDS User s Guide

Example: A Dipole Antenna 2 Figure 14 Save Field Snapshots Tab 4 Choose a beginning time step of 10, an ending time step of 2000, and an increment of 10. 5 Click the Add Sequence button to add the sequence to the list in the window. AMDS User s Guide 31

2 Example: A Dipole Antenna Saving the FDTD Project To save the project, 1 Click the Save Project button on the main toolbar. A dialog box is displayed enabling you to save your project. 32 AMDS User s Guide

Example: A Dipole Antenna 2 Running the Analysis With the geometry and the project defined, the analysis may be carried out. To start the analysis, 1 Choose Results > Run Calculation. 2 Click the Calculate button to begin the calculation. During the analysis, the display will show the current time step and percent of the task completed. An estimate of time remaining to finish the calculation is provided as shown in Figure 15. AMDS User s Guide 33

2 Example: A Dipole Antenna Figure 15 Running the Analysis 34 AMDS User s Guide

Example: A Dipole Antenna 2 Examining the Results Once the analysis is complete, the results can be viewed. View Field Sequence To view the field sequence, 1 From the Geometry > View window, click the Field Controls button to display the Field Controls window. 2 At the top of the window you will see a field tree as shown in Figure 16. Double-click on the branch under Field Snapshot Sequence, which is the sequence defined when you requested results. That sequence now appears under Loaded Fields. AMDS User s Guide 35

2 Example: A Dipole Antenna Figure 16 Field snapshot sequence tree and controls 3 Now the Field Sequence Controls can be used to display the movie. The center button stops the sequence. Buttons to the right of it will start the sequence, take one step ahead, fast forward, and jump to the end, respectively. 36 AMDS User s Guide

Example: A Dipole Antenna 2 Buttons to the left of the stop button perform the same functions in reverse. 4 Various displays can be created by changing specifications in the menus for Field, Scale, Increment and Interpolation. Four viewing modes can be accessed from the Mode menu. Once the desired selection is made, click Apply. Figure 17 Normal (2D) Field Display AMDS User s Guide 37

2 Example: A Dipole Antenna Figure 18 2D Vector Field Display 38 AMDS User s Guide

Example: A Dipole Antenna 2 Figure 19 3D Field Display AMDS User s Guide 39

2 Example: A Dipole Antenna Figure 20 3D Vector Field Display Exporting the Animation to an MPEG File Transient field sequences can be exported to MPEG movie files for viewing on other computers by clicking the Export MPEG button. The export is an MPEG file, 1 Specify a file name for the animation. 2 Specify a frame rate in snapshots per second (snapshot is a single screen shot). The final movie is encoded at a standard 30 frames per second. However, the rate in snapshots per second can be specified. 40 AMDS User s Guide

Example: A Dipole Antenna 2 3 Check Automatically Grab Snapshots. This option tells the Field Controls window to inform the MPEG Exporter each time it updates the current field. 4 Play the transient field sequence again so that the frames can be recorded. 5 De-select Automatically Grab Snapshots and click Encode to create the MPEG file. C:\Application_files\Local_Examples\AMDS\examples\dipole.mpg Figure 21 MPEG File Export Dialog Box AMDS User s Guide 41

2 Example: A Dipole Antenna C:\Application_files\Local_Examples\AMDS\examples\dipole.fdtd Figure 22 Specifying the Graphs to Display Plotting To plot your results, 1 Move to the Results > Plots tab to graph the available output data. 2 Choose Port 1... from the list of Available Data of Selected Type and add it to the Data Selected For 42 AMDS User s Guide

Example: A Dipole Antenna 2 Plotting list by clicking the Add Selected Plot button as shown in Figure 22. 3 Clicking Edit Plot Parameters displays the Plot Parameters dialog box where plot parameters are specified as shown in Figure 23. Figure 23 The Plot Parameters Window AMDS User s Guide 43

2 Example: A Dipole Antenna 4 Set the X axis label to Time (ns) and the Y axis label to Voltage. 5 Click the Apply button and close the Plot Parameters dialog box. 6 From the Plots tab, click the Plot button at the bottom right of the window and the graph is displayed as shown in Figure 24. Figure 24 Graph of Voltage verses Time 44 AMDS User s Guide

Example: A Dipole Antenna 2 Frequency Domain Results Frequency domain data can be plotted by performing an FFT on available data from the FFT tab. However, some frequency domain data may be available after a run without requiring the use of this tab. To view frequency domain data, 1 Choose Port 1 from the list. 2 Click the Calculate button. The FFT is carried out and progress is shown in the Status window. Figure 25 The FFT Tab 3 Return to the Plots tab. 4 Choose Plot vs. Frequency as the data type to plot and FFT of Port 1 as the data. AMDS User s Guide 45

2 Example: A Dipole Antenna 5 Click the Add Selected Plot button to add the data to the Data Selected For Plotting list. Also change the axes labels to represent the new data. 6 Click the Plot button to display the graph as shown in Figure 26. Since this is a sine wave excitation, the energy is localized around the excitation frequency. For a transient pulse excitation, the plot would indicate the frequency spectrum of the voltage at the port. Figure 26 Graph of Voltage vs. Frequency 46 AMDS User s Guide

Example: A Dipole Antenna 2 Steady State Analysis The power and efficiency of the antenna is displayed on the Results > Power/Efficiency tab as shown in Figure 28. If the 3D far-zone pattern has been calculated, this can also be displayed. To calculate the far-zone patterns, 1 Select the Far-Zone tab as shown in Figure 27. Calculate a 2-D constant theta pattern at theta=90 and the 3-D Far-Zone display. 2 The 2D pattern is defined by setting Phi=0 and Final Phi=360. Click Add. Then select the 3-D Far-Zone Pattern with 2.5 increments in both angular directions. 3 Set Phi to calculate from 0 to 360 and theta to calculate from -180 to 180. Again click Add and then Calculate. 4 After the data is calculated, the 2-D far-zone antenna gain pattern is available on the Plots tab when Plot vs. Angle is selected. The 3-D antenna pattern display is available in the Results > Power/Efficiency tab, as shown in Figure 28, and the Field Control Panel. To display the 3-D antenna pattern, 1 Move to the Geometry > View window. 2 Click the Field Controls button to display the Field Controls window. 3 At the top of the window you will see a field tree. Double-click on the branch under Far-Zone Fields and select the antenna pattern to be displayed. Also select the options to show the theta and phi axes. The resulting display is shown in Figure 29. AMDS User s Guide 47

2 Example: A Dipole Antenna Figure 27 Far-Zone Pattern Calculation Figure 28 Power and Efficiency with Far-Zone Display 48 AMDS User s Guide

Example: A Dipole Antenna 2 Figure 29 3-D Antenna Gain Pattern To display the 2D pattern, 1 Move to the Plots tab 2 Select the line of data and click the Add Selected Plot button. 3 Click the Edit Plot Parameters button to edit the axis labels in the Edit Plot Parameters window. 4 Return to the Plot tab and click Plot to see the display shown in Figure 30 for the Ephi polarization. AMDS User s Guide 49

2 Example: A Dipole Antenna 5 Figure 31 shows the polar graph of the same data. To display the polar format, select the Polar option in the Edit Plot Parameters window. The angular data may be varied to show graphs for different conditions. For example a 360 degree plot may also be obtained by specifying Final Phi=360. Figure 30 Antenna Gain vs. Phi 50 AMDS User s Guide

Example: A Dipole Antenna 2 Figure 31 Polar Display of Antenna Gain The feed impedance is displayed on the Results > Port Data tab as shown in Figure 32. AMDS User s Guide 51

2 Example: A Dipole Antenna Figure 32 Feed Point Impedance Antenna diversity and other data are also available in the Antenna tab. Although not used here, this is displayed in Figure 33. 52 AMDS User s Guide

Example: A Dipole Antenna 2 Figure 33 Further Antenna Data AMDS User s Guide 53

2 Example: A Dipole Antenna 54 AMDS User s Guide

Agilent W2100 Antenna Modeling Design System User s Guide 3 Example: A Low Pass Filter Modeling the Geometry 57 Generating the Mesh 68 Adding the Wire Feeds 71 Adding a PEC Boundary Condition to Model the Ground Plane 76 Adding the Source and Load Ports 77 Specifying the Input Waveform 79 Field Snapshot Sequence 80 Running the Analysis 81 Examining the Results 82 Example: Adding Calibration to the Low Pass Filter 89 This example illustrates the analysis of a low pass filter. A Gaussian pulse is used as the source waveform to provide a wide bandwidth frequency response from a single simulation. The frequency range for this device is 0 to 13 GHz. Agilent Technologies 55

3 Example: A Low Pass Filter Data files for AMDS examples are available from the Agilent EEsof EDA Web site. For more information on downloading the example data file(s), refer to Data Files for Examples on page 8. 56 AMDS User s Guide

Example: A Low Pass Filter 3 Modeling the Geometry This section covers information on modeling the geometry of the low pass filter. The Substrate With AMDS running, 1 Select Geometry > View. The Geometry > View tab is shown in Figure 34. Figure 34 The Geometry > View Tab 2 Add a new material for the substrate with relative permittivity of 3 using the material selector in the Geometry > View tab shown in Figure 35. Figure 35 The Material Selection Menu AMDS User s Guide 57

3 Example: A Low Pass Filter 3 To add the material, click in the white center panel to display the menu shown in Figure 36 and select Add Material. Figure 36 Adding a Material 4 The material can be defined in the window shown in Figure 37. Figure 37 Material Definition 58 AMDS User s Guide

Example: A Low Pass Filter 3 5 Define the substrate material as shown in Figure 38. Figure 38 Material Values 6 Use the Block button to open the Block dialog box. 7 Make the 12 x 10 x 0.64 mm substrate geometry with upper surface at z=0 as shown in Figure 39. AMDS User s Guide 59

3 Example: A Low Pass Filter Figure 39 Block Dialog 8 Click Add and then Close on the Block dialog box to obtain the geometry as shown in Figure 40. 60 AMDS User s Guide

Example: A Low Pass Filter 3 Figure 40 Displaying the Substrate The Strip Line To model the first rectangular section of the thin conducting surface layer forming the filter, 1 Click the Thin Rectangular Plate button. 2 Complete the dialog shown in Figure 41 to select PEC material and form a 2 x 0.56 mm conducting plate in the z=0 plane just at the surface of the substrate: AMDS User s Guide 61

3 Example: A Low Pass Filter Figure 41 Circuit Input Geometry Definition 3 Clicking Add and then Close places the first part of the circuit on the substrate as shown in Figure 42. 62 AMDS User s Guide

Example: A Low Pass Filter 3 Figure 42 Displaying the Circuit on the Substrate 4 In the same way, the next two parts of the circuit should be added by completing the dialogs shown in Figure 43. AMDS User s Guide 63

3 Example: A Low Pass Filter Figure 43 Further Circuit Input Geometry Definition This should give the following geometry as shown in Figure 44. 64 AMDS User s Guide

Example: A Low Pass Filter 3 Figure 44 Displaying Additions to the Circuit To complete the circuit, parts of the existing circuit will be copied and translated to new locations. To do this, 1 Select the IN object, then press and hold the right mouse button. 2 Select Edit/Transform Operations > Copy And Paste. By completing the menu as shown in Figure 45, the IN object is copied to a new location: AMDS User s Guide 65

3 Example: A Low Pass Filter Figure 45 Making a Copy of the Circuit Elements This copied object can be renamed to OUT by using Edit/Transform Operations > Rename. 3 Repeat the process to create C2 by selecting Edit/Transform Operations > Copy And Move on the object C1, using the menu entries shown in Figure 46 and editing the name. Figure 46 Making Further Copies of the Circuit Elements 66 AMDS User s Guide

Example: A Low Pass Filter 3 The circuit and substrate model are shown in Figure 47 with object C2 selected in the object list and therefore highlighted in the geometry view. Figure 47 Displaying the Copied Circuit Elements AMDS User s Guide 67

3 Example: A Low Pass Filter Generating the Mesh It is necessary to generate the mesh before adding wire feeds and specifying the boundary conditions, ports, sources and loads. To generate the mesh, 1 Select the Mesh tab as shown in Figure 48. Figure 48 The Geometry > Mesh Tab 2 Set the mesh cell size to 0.1 mm as shown in Figure 49. Figure 49 Setting the Cell Size 68 AMDS User s Guide

Example: A Low Pass Filter 3 3 Ensure that the lock icon is closed once the cell sizes are set. 4 Confirm that the units are set to millimeters and the Non-uniform padding is specified. The z=0 number of cells for non-uniform padding will position the lower surface of the substrate at z=0 which will put it in contact with a conducting boundary at z=0 to be specified later. The z=20 cell boundary allows sufficient space above the filter for the fields to be calculated and radiated fields to be absorbed. The Max Frequency for this cell size of about 300 GHz is well above the upper frequency of interest for this device, so you could use much larger cells for this calculation. However, the memory required for this cell size is only approximately 35 Mbytes so these small cells can be used to increase accuracy without requiring very much computer memory or calculation time. If you decide to use larger cells, one guideline is that the cell size should be small enough to allow for at least three cells over the thickness of the substrate. With this cell size you will have 6 cells which are more than sufficient. AMDS User s Guide 69

3 Example: A Low Pass Filter Figure 50 Generating the Mesh 5 With the menu entries complete, click the Generate Mesh button to create the new mesh. 70 AMDS User s Guide

Example: A Low Pass Filter 3 Adding the Wire Feeds To add the wire feeds, 1 Switch back to View (shown in Figure 51) and ensure that the Mesh Mode is displayed. Figure 51 The Geometry > View Tab 2 Select the YZ planar view and set the Slice indicator to 16. This is the first plane of the substrate and circuit in the model where the input feed will be located. 3 Position this view in a similar location to that shown in Figure 52 to see a more detailed geometry and mesh. AMDS User s Guide 71

3 Example: A Low Pass Filter Figure 52 Viewing the Edge of the Substrate 4 Click the Wire button. The Wire dialog box appears. 5 Set the Wire dialog box as shown in Figure 53. The coordinates of the wire end points can be obtained by moving the mouse pointer to the end point positions in the view shown in Figure 52 and reading the coordinates displayed in the window. 72 AMDS User s Guide

Example: A Low Pass Filter 3 Figure 53 Defining the Wire The wire feed appears as shown in Figure 54. AMDS User s Guide 73

3 Example: A Low Pass Filter Figure 54 Displaying the Wire 6 Now change the Slice indicator to 136, the last plane of the substrate and circuit assembly, 12 mm from the input feed point. In the same way, define a wire load using the values shown in the menu in Figure 55. 74 AMDS User s Guide

Example: A Low Pass Filter 3 Figure 55 Defining the Second Wire 7 Save the geometry. AMDS User s Guide 75

3 Example: A Low Pass Filter Adding a PEC Boundary Condition to Model the Ground Plane To add a PEC boundary condition to model the ground plane, 1 Select the Run Parameters > Outer Boundary tab and set the lower z-plane to be PEC as shown in Figure 56. This PEC condition represents the ground plane of the filter. Figure 56 Defining the Ground Plane Boundary Condition NOTE The information window referring to far-field calculations are not valid with any outer boundaries set to non-absorbing. 76 AMDS User s Guide

Example: A Low Pass Filter 3 Adding the Source and Load Ports To add the source and load ports, 1 Set the Slice indicator back to 16, so that a source port can be added to the wire labeled source. 2 Select the port icon and move the cursor to edge location (16, 66, 1) with the z-directed port high-lighted. 3 Right-click and select Add Default Port. 4 To check the values that are set for this default port, right-click on the green marker and select Edit. The parameters are displayed in the Components/Ports tab as shown in Figure 57. Figure 57 Defining the Voltage Source Port AMDS User s Guide 77

3 Example: A Low Pass Filter 5 Switch back to the Geometry > View tab. 6 Move back to Slice 136 and repeat the procedure at the z-directed edge location (136, 66, 1) to create a 50Ω load port as shown in Figure 58. Note that the Voltage parameter should be set to Passive Load. Figure 58 Defining Load Port 7 Returning to the Geometry > View enables you to view the ports (as green markers). Deselect the icon. 78 AMDS User s Guide

Example: A Low Pass Filter 3 Specifying the Input Waveform To specify the input waveform, 1 Select the Run Parameters > Waveform tab. 2 Specify a Gaussian input waveform with a pulse width set to 64 time steps. 3 Use the automatic convergence that is set by default, as shown in Figure 59. Figure 59 Defining the Input Waveform AMDS User s Guide 79

3 Example: A Low Pass Filter Field Snapshot Sequence It is necessary to specify the required output before running the analysis. To add a field movie sequence, 1 Select the Request Results > Save Field Snapshots tab and complete the tab as shown in Figure 60. 2 To retain the values in the saved list, click the Add Sequence button. The requested sequence will store the field distribution in slice 7 (xy-plane) of the model between time steps 50 and 2000 in increments of 50 steps. This may then be viewed following completion of the analysis. Figure 60 Defining the Field Snapshots 3 Save the geometry and project. 80 AMDS User s Guide

Example: A Low Pass Filter 3 Running the Analysis To run the analysis, 1 Select the Results > Run Calculation tab. 2 Click the Calculate button. AMDS User s Guide 81

3 Example: A Low Pass Filter Examining the Results Although the automatic convergence has been set, it is good practice to view the waveforms in the model to ensure that the energy has completely dissipated, providing complete convergence. To do this: 1 Open the Plots tab as shown in Figure 61. To do this select Results > Plots > Plots vs. Time and select the Port 1 and Port 2 Voltages vs. time to plot as shown in Figure 61. C:\Application_files\Local_Examples\AMDS\examples\lpf\lpf.fdtd Figure 61 Port Voltage PLOT VS TIME 82 AMDS User s Guide

Example: A Low Pass Filter 3 The result plot shown in Figure 62 shows that both port voltages have decayed to zero and therefore the AMDS calculation has converged. Figure 62 The Voltage Waveform verses Time To view the field snapshot, 1 Select the Geometry > View tab and click the Field Control button. 2 From the resulting dialog box, select the appropriate sequence as shown in Figure 63. AMDS User s Guide 83

3 Example: A Low Pass Filter Figure 63 Loading the Field Snapshots 3 Double-click the mouse to display the appropriate mesh slice and play controls. The field display can be controlled as required. A typical distribution is shown in Figure 64. 84 AMDS User s Guide

Example: A Low Pass Filter 3 Figure 64 Display of the Field Snapshots Sequence 4 The material view can be turned off with the yellow lightning bolt icon at right to allow clearer view of the fields. S-parameters vs. frequency are available to plot in the Results > Plots > Plot vs. Frequency window. The default FFT (fast fourier transform) size may be a little small for a smooth plot since we have relatively small cells for this frequency range. To obtain the S-parameters vs. frequency with a finer frequency increment, 1 Select Results > FFT. 2 Select S-Parameters. 3 Select an FFT size of 256k. 4 Click the Calculate button to perform the FFT on the time domain results at the ports. 5 Once completed, select Results > Plots. AMDS User s Guide 85

3 Example: A Low Pass Filter 6 Select Plot vs. Frequency and add the S21 vs. freq to the Data Selected For Plotting list as shown in Figure 65. C:\Application_files\Local_Examples\AMDS\examples\lpf\lpf.fdtd Figure 65 Selecting the S-parameter Graph Data 7 Click the Edit Plot Parameters button to set the rectangular graph scales as shown in Figure 66. 86 AMDS User s Guide

Example: A Low Pass Filter 3 Figure 66 Defining the Graph Parameters 8 Select the Plot to display the S 21 vs. Frequency graph as shown in Figure 67. 9 The same procedure can be used for S 11 vs. Frequency (also shown in Figure 67) by setting the limits of the y-axis from -50 to 0. AMDS User s Guide 87

3 Example: A Low Pass Filter Figure 67 Displaying the S-parameter The desired low pass filter characteristic is clearly shown over the entire frequency band of the filter from one AMDS calculation. 88 AMDS User s Guide

Example: A Low Pass Filter 3 Example: Adding Calibration to the Low Pass Filter This example calibration is an addition to the Low Pass Filter example and illustrates the calibration of a multi-port circuit. The data file(s) for this example are available from the EEsof Knowledge Center under the AMDS downloads in antenna.zip. For more information on downloading the example data file(s), refer to Data Files for Examples on page 8. Pre-processing 1 Reopen the project named filter.fdtd created in the previous Low Pass Filter example. 2 Resave the project as CalibratedFilter.fdtd and the geometry as CalibratedFilter.id. AMDS User s Guide 89

3 Example: A Low Pass Filter Adding the calibration 1 Select Geometry > View. In Mesh mode, click in the YZ plane. Go to slice 16 and zoom in on the region around the feed wire. Figure 68 Settin up the calibration 90 AMDS User s Guide

Example: A Low Pass Filter 3 2 Click the Calibration Tool button. In the YZ plane in slice 16, right-click on the feed and select the port. Figure 69 AMDS User s Guide 91

3 Example: A Low Pass Filter 3 While still in the YZ plane, go to slice 28 (about 1.2 mm away from the feed). Right-click in a cell located just above the ground plane and beneath the middle of the microstrip. Select Start calibrated port voltage line. Figure 70 92 AMDS User s Guide

Example: A Low Pass Filter 3 4 Draw a voltage line from the ground plane to the microstrip. Right-click when the arrow of the voltage line touches the strip and select End calibrated voltage line. Figure 71 AMDS User s Guide 93

3 Example: A Low Pass Filter Figure 72 94 AMDS User s Guide

Example: A Low Pass Filter 3 5 Right-click the mesh cell that is just below and to the left of the microstrip. Select Start calibrated port current contour. Figure 73 AMDS User s Guide 95

3 Example: A Low Pass Filter 6 Draw a current contour around the microstrip. Select End calibrated port current contour. Figure 74 96 AMDS User s Guide

Example: A Low Pass Filter 3 Figure 75 AMDS User s Guide 97

3 Example: A Low Pass Filter 7 In the YZ plane select slice 136. Right-click the feed and select the port. Figure 76 98 AMDS User s Guide

Example: A Low Pass Filter 3 8 In the YZ plane select slice 124 (about 1.2mm away from the feed). Right-click on a cell located just above the ground plane and beneath the middle of the microstrip. Select Start calibrated port voltage line and draw a voltage line from the ground plane to the microstrip. Right-click when the arrow of the voltage line touches the strip and select End calibrated port voltage line. Figure 77 AMDS User s Guide 99

3 Example: A Low Pass Filter 9 Right-click on the mesh cell just below and to the left of the microstrip. Select Start calibrated port current contour and draw a current contour around the microstrip. Select End calibrated port current contour. Figure 78 100 AMDS User s Guide

Example: A Low Pass Filter 3 10 Save the geometry and the project. You will receive the warning shown below. For the calibration algorithm to work properly, the directions of the voltage lines and current contours have to be chosen carefully. The current contours must be directed from the non-calibrated feed to the actual structure. The voltage line must point inwards of the current contour. This can be easily checked by going back to the Solid view and by zooming in on the calibrated port. When these conditions are not met, a warning is generated when saving the project. Figure 79 Correct AMDS User s Guide 101

3 Example: A Low Pass Filter Figure 80 Incorrect 102 AMDS User s Guide

Example: A Low Pass Filter 3 11 In Mesh mode, select the YZ plane and select slice 124. Click the Calibration tool button. Right-click the current contour and select Reverse current contour. 12 Resave the geometry and the project. AMDS User s Guide 103

3 Example: A Low Pass Filter Running the Simulation 1 Select Run Parameters > Components/Ports, ensure the Batch all simulation feeds flag is set to On. This will force AMDS to do two simulations, the first one with feed 1 active and the second one with feed 2 active. If the Batch all simulation feeds flag is off, no calibration will occur. Figure 81 104 AMDS User s Guide

Example: A Low Pass Filter 3 2 Select the second feed and change it from a Passive Load to a Series Voltage, click Update Component. Figure 82 AMDS User s Guide 105

3 Example: A Low Pass Filter Figure 83 3 Select Results > Run Calculation. 4 If an Acceleware FDTD accelerator is available, check the Use Acceleware FDTD Acceleration if available checkbox. 5 Click Calculate. Examining the results 1 Once the computation is complete, choose Results > Plot 2 Select Plot vs. Frequency and add the magnitude of the s11 vs. Freq. and the Calibrated s11 vs. Freq data to Data Selected for Plotting. 3 Click the Edit Plot Parameters button. Set X Min =0, X Max = 13, Y Min = -50, and Y Max = 0. Click Apply and Close. 106 AMDS User s Guide

Example: A Low Pass Filter 3 4 To view to S-parameters, click Plot. A display of the uncalibrated and calibrated S 11 is shown below. Figure 84 Calibrated and uncalibrated S 11 plot. AMDS User s Guide 107

3 Example: A Low Pass Filter 5 Repeat this procedure for the S 12 parameter. Figure 85 Calibrated and uncalibrated S 12 plot. 108 AMDS User s Guide

Agilent W2100 Antenna Modeling Design System User s Guide 4 Example: A Patch Antenna Constructing the Geometry 111 Creating the Mesh 122 Creation of Feed Line and Port 129 Run Parameters 134 Requesting Results 136 Running the Analysis 137 Examining the Results 138 Example: Adding Calibration to the Patch Antenna 146 Agilent Technologies 109

4 Example: A Patch Antenna This example involves a microstrip patch antenna and is based on the paper "Applications of the Three Dimensional Finite Difference Time Domain Method to the Analysis of Planar Microstrip Circuits" by Sheen et al in the July 1990 issue of IEEE Transactions on Microwave Theory and Techniques, pp 849-856. A Gaussian pulse is used as the source waveform. An example of the use of adaptive mesh is also included. Data files for AMDS examples are available from the Agilent EEsof EDA Web site. For more information on downloading the example data file(s), refer to Data Files for Examples on page 8. 110 AMDS User s Guide

Example: A Patch Antenna 4 Constructing the Geometry This section covers constructing the geometry. Materials The substrate material (a dielectric material) should be defined as: σ = 0.0, ε r = 2.2 To enter these materials into the geometry, 1 Select the Geometry > View. 2 Open the Material Selector. 3 Click Add Material. The Edit Electrical Material dialog box is displayed as shown in Figure 86. This dialog box is used to enter the material parameters. AMDS User s Guide 111

4 Example: A Patch Antenna Figure 86 The Edit Electrical Material Dialog Box Substrate Geometry The substrate will be created using a rectangular block. 1 Click the rectangular Block button on the geometry toolbar. 112 AMDS User s Guide

Example: A Patch Antenna 4 The Block dialog box is displayed as shown in Figure 87. Figure 87 The Block Dialog Box 2 Name the object Substrate. 3 Set the Units to Centimeters. 4 Set the material as Material 2, and use the following parameters to create the substrate block: Corner Point: (0, 0, 0) Change in: (2.2951, 2.96, 0.0795) 5 Click the Add button to add the block to the geometry. 6 Click the Close button to dismiss the dialog. AMDS User s Guide 113

4 Example: A Patch Antenna Patch Geometry There are a number of methods to create the patch. The 2D Editor can be used with either two squares or a single polygon. Two thin rectangular plates can be used directly in the 3D geometric modeler or a single plate can be used and areas cut away using Boolean operations. The latter will be used here. Creating the Base Patch To create the base patch, 1 Select the Thin Rectangular Plate button to open the Thin Rectangular Plate dialog box shown in Figure 88. 2 Complete the dialog box as shown using the following parameters: Name: Units: Patch Centimeters Center Point: 1.128, 1.56, 0.0795 Width: 1.244 Depth: 2.0 Plane: XY 3 Ensure that PEC material is selected. 114 AMDS User s Guide

Example: A Patch Antenna 4 Figure 88 The Thin Rectangular Plate Dialog Box 4 Click the Add button to add your changes. 5 Click the Close button to dismiss the dialog box. The resulting view will look similar to that shown in Figure 89. AMDS User s Guide 115

4 Example: A Patch Antenna Figure 89 The Substrate and Base Patch An area will be cut away from this rectangular plate using a Boolean subtraction operation. To create the cutting block, 1 Select the rectangular Block button on the geometry toolbar to bring up the Block dialog box, as shown in Figure 90. 116 AMDS User s Guide

Example: A Patch Antenna 4 2 Set the parameters to: Name: Units: cut1 Centimeters Corner Point: 0, 0, -1 Change in: 0.7002, 0.96, 2 Figure 90 The Block Dialog Box 3 Click the Add button to add your changes. 4 Click the Close button to dismiss the dialog box. The resulting view will look similar to that shown in Figure 91. AMDS User s Guide 117

4 Example: A Patch Antenna Figure 91 The Substrate, Base Patch and Cutting Block 5 Hold down the Ctrl key and click the right mouse button to select both the Patch and cut1 objects. 6 With both objects selected, use a right mouse button click to display the menu shown in Figure 92. 118 AMDS User s Guide

Example: A Patch Antenna 4 Figure 92 Boolean Operations 7 Select the Subtract menu item to display the Subtract Objects dialog box as shown in Figure 93. AMDS User s Guide 119

4 Example: A Patch Antenna Figure 93 Subtracting Objects 8 Ensure that cut1 is being subtracted from Patch. If this is not the case, click the Reverse Order button. 9 Click OK to dismiss the Subtract Objects dialog box. 10 Repeat the procedure for a second block with the following parameters: Name: Units: cut2 Centimeters Corner Point: 0.9336, 0, -1 Change in: 1, 0.96, 2 The resulting geometry should look like that shown in Figure 94. 120 AMDS User s Guide

Example: A Patch Antenna 4 Figure 94 The Final Shape of the Patch AMDS User s Guide 121

4 Example: A Patch Antenna Creating the Mesh This section describes how to create the mesh. Choosing Cell Size The maximum frequency of interest in this problem is 20 GHz. Find the maximum possible cell size using the equation: L max = c -------------- 10 f Where L max is the maximum cell dimension c is the speed of light, 3x10 8 m/s f is the frequency of excitation (Hz) 3 10 8 L max = ---------------------------------- 10 75 10 9 = 0.0015cm cell When choosing a cell size, the dimensions of the geometry must also be considered. In this case, the dielectric slab is 0.0795 cm thick, and at least 3 cells should be used over the thickness of the substrate to accurately calculate the fringing fields. As adaptive meshing will be used to achieve this, 1 Select a base cell size of 0.06 cm in all three directions as shown in Figure 95. 2 Click the Lock button once the base cell sizes are set. 3 Select Non-uniform padding and select all padding to be 20 cells except for the Lower z, this should be set to zero. 4 Click the Generate Mesh button. 122 AMDS User s Guide

Example: A Patch Antenna 4 Figure 95 The Settings in the Mesh Tab Adaptive Meshing Under certain circumstances, especially for large problems, it may be advantageous to adaptively mesh the geometry. This essentially enables you to set fine cells where the geometry or field behavior requires high spatial resolution and larger cells elsewhere in the space, thus reducing the overall number of cells and computation time. Examples of these situations include the volume surrounding a feed point, the edge of a microstrip line or coupler, in the near field of an antenna, or in and around an area of particular interest. For the Patch Antenna example, it will be useful to mesh the principle features of the patch and feed geometry in fine cells while using a coarser grid for the surrounding area. The largest cell size in the project is referred to as the AMDS User s Guide 123

4 Example: A Patch Antenna base or primary cell size and all adaptive mesh regions will be filled with cells which are smaller than this base cell size. For this example, the base cell size has been set to 0.06 cm. To set the adaptive mesh regions in this model, 1 Click the Adaptive Mesh Regions. This will produce a window as shown in Figure 96. Figure 96 The Adaptive Mesh Regions Tab 2 Begin by creating an x-directed adaptive mesh region. This will reduce the x cell dimension in the designated 124 AMDS User s Guide

Example: A Patch Antenna 4 region. Click the X radio button to indicate the adaptive mesh is to be x-directed. 3 Click the radio button indicating Ratio to primary cell size. 4 Click in the window which is active and type 2 to signify the ratio of the base cell size to the adaptive mesh cells is 2:1. 5 Locate the Bounds of Constant region near the bottom of the Adaptive Mesh window. Enter 1.675 cm as the START of the region and 1.825 cm as the STOP dimension. 6 Click Add to modify the x-directed cell profile to display the Adaptive mesh region and the transition regions into and out of the region of fine cells. This is shown in Figure 97. Figure 97 X-Directed Adaptive Mesh Region Specified AMDS User s Guide 125

4 Example: A Patch Antenna 7 Repeat the same procedure using the following parameters for further adaptive mesh regions: X-directed, 4:1 ratio, START=0.425cm STOP=0.95cm Y-directed, 2:1 ratio, START=0.5cm STOP=0.625cm Y-directed, 2:1 ratio, START=0.925cm STOP=1.025cm Y-directed, 2:1 ratio, START=2.5cm STOP=2.6cm Z-directed, 5:1 ratio, START=0cm STOP=0.085cm The adaptive mesh tab should look similar to that shown in Figure 98. Figure 98 All Adaptive Mesh Regions 8 Move to the Mesh tab and click the Generate Mesh button again. 9 Then move to the View tab and the display should be similar to that shown in Figure 99. 126 AMDS User s Guide

Example: A Patch Antenna 4 10 Ensure that Mesh Mode is selected above the view and the Slice number is set to 8. Figure 99 Mesh View with Adaptive Mesh Regions Shown It is important to mention four points regarding Adaptive mesh here: The transition from the base cell size to the adaptive mesh cell size occurs gradually over several cells in both the transition from base to adaptive as well as adaptive to base cell sizes. The rate of transition is set automatically and is not a user variable parameter. When, for instance, an x-directed adaptive mesh is defined, the region over which the adaptive mesh cells exist is a parallelepiped extending from the Start to Stop dimensions in x, and will extend to the boundary of the grid in y, and z. As has been seen, multiple adaptive mesh regions can be created in a given direction. AMDS User s Guide 127

4 Example: A Patch Antenna Changing the mesh by creating adaptive mesh regions will not modify the project geometry (up to the resolution of cell size), but will change the total number of cells in a given direction. This is important to remember when referencing objects or boundaries by their FDTD cell number coordinates. 11 Next, the feed and excitation will be defined for this project. At this point make sure to save the geometry. 128 AMDS User s Guide

Example: A Patch Antenna 4 Creation of Feed Line and Port In Geometry > View, Mesh Mode, (the mode selector is located above the geometry drawing space) a feed line will be created for the port. The feed line should begin at the center of the lower (minimum y) edge of the lower rectangle and continue in the z direction until it intersects the ground plane. The ground plane, a metal layer underneath the patch antenna, is not shown in the geometry. It is defined by the outer boundary conditions to be specified later. The patch antenna is made up of the ground plane, the dielectric substrate, and the air/dielectric layer in which lies the two-dimensional, PEC patch. The four windows in the middle of the Geometry > View window show four views of the geometry. 1 Click on the second box to show the yz plane. 2 Using the Slice selector at the top of the drawing window, move to slice 32 of the zx plane. 3 Click the Wire button and specify a wire having the following parameters: Name: Units: feed Centimeters Point 1: 0.815, 0.56, 0 Point 2: 0.815, 0.56, 0.0795 Material: PEC The Wire dialog box is shown in Figure 100. AMDS User s Guide 129

4 Example: A Patch Antenna Figure 100 Wire Feed Parameters The feed should be visible as shown in Figure 101. 130 AMDS User s Guide

Example: A Patch Antenna 4 Figure 101 Wire Feed Shown in Mesh View 4 AMDS provides an button for placing ports and components. Select the ports and components button and move the cursor such that the marker is located on the wire next to the ground plane (56, 32, 1) as shown in Figure 101. 5 Right-click at this location and select the Add default feed option. 6 To verify settings for the port, right-click on this cell edge as shown in Figure 102 and select Edit. The Component/Ports tab is displayed with the port parameters pre-selected to match the cursor position. Here a 50 Ohm voltage source is to be used to excite the antenna. AMDS User s Guide 131

4 Example: A Patch Antenna Figure 102 Positioning the Port 132 AMDS User s Guide

Example: A Patch Antenna 4 Figure 103 Excitation Port Specification 7 Deselect the Component/Port button and save the geometry and project. AMDS User s Guide 133

4 Example: A Patch Antenna Run Parameters This section describes how to run the parameters. Setting the Outer Boundaries of the Model To set the outer radiation boundary conditions, including a ground plane underneath the substrate, 1 Choose the Run Parameters > Outer Boundary. 2 Set the xy plane at z = cell 1 to PEC. All other boundaries should remain at the default setting of Absorbing, using the PML condition with 7 layers. 3 Note and clear the message box. Figure 104 Setting the Outer Boundary Conditions 134 AMDS User s Guide

Example: A Patch Antenna 4 Define the Waveform To define the waveform, 1 Choose the Run Parameters > Waveform. 2 Choose Gaussian waveform and a Pulse Width of 64 time steps. 3 For Simulation termination criteria, select the Automatic Convergence option and change the Convergence Threshold to -40dB. 4 Click Advanced to open the Advanced window and set the Maximum Calculation to 15000 time steps. Figure 105 Specifying the Waveform AMDS User s Guide 135

4 Example: A Patch Antenna Requesting Results This section describes how to request results. Field Snapshots To add a field snapshot sequence to the requested output, 1 First return to the Geometry > View window. 2 Right-click anywhere in the plane of the patch (xy at z = 8). 3 On the pop-up menu, choose Save Data > Field snapshots. This opens and displays the Request Results > Save Field Snapshots and completes it with the values appropriate for the plane selected. 4 Choose a starting time step of 20, an ending time step of 1000, and an increment of 10. 5 Click the Add Sequence button to add the sequence to the list. 6 Make sure to save the FDTD project file. Figure 106 Saving the Transient Field Sequence Settings 136 AMDS User s Guide

Example: A Patch Antenna 4 Running the Analysis Now that the geometry and the project have been defined, run the calculation. 1 Choose Results > Run Calculation. 2 Click the Calculate button to start the calculation. 3 Once the calculation is complete, the output can be viewed in several different modes. AMDS User s Guide 137

4 Example: A Patch Antenna Examining the Results This section describes how to examine the results after running the analysis. View Field Snapshot Sequence To view the field snapshot sequence, 1 From the Geometry > View, click the Field Controls button to display the Field Controls window. 2 Expand Field Snapshot Sequence and double-click on the sequence shown which will allow viewing of the sequence by operating the controls. The data can be viewed in four modes which are selected in the Field Controls window. 138 AMDS User s Guide

Example: A Patch Antenna 4 Figure 107 Normal Field AMDS User s Guide 139

4 Example: A Patch Antenna C:\Example_files\Local_Examples\AMDS\examples\patch\patch.fdtd Figure 108 Graph Selection for Voltage vs. Time 140 AMDS User s Guide

Example: A Patch Antenna 4 Plotting To make sure that the calculation has converged, plot the voltages at the port. To do this, 1 Select the Results > Plots and add the voltage vs. time data to the Data Selected for Plotting, as shown in Figure 108. The plots are shown in Figure 109. As can be seen, the voltage has decayed to a negligible value. Figure 109 Graph of Voltage vs. Time AMDS User s Guide 141

4 Example: A Patch Antenna C:\Example_files\Local_Examples\AMDS\examples\patch\patch.fdtd Figure 110 Graph Selection for S11 vs. Frequency 2 Choose Results > Plots. 3 Choose Plot vs. Frequency as the data type and the S-parameter s11 vs. Freq as the data to plot. 4 Click the Add Selected Plot button to add the S 11 results to the lower window. 142 AMDS User s Guide

Example: A Patch Antenna 4 5 Since a much smaller than necessary cell size was used, data is available at frequencies much higher than those that we are interested in here. To focus on the frequencies of interest, the graph limits should be set. Click the Edit Plot Parameters button. 6 Limit the maximum x axis value to 20 GHz. 7 Click the Apply button. 8 Click the Close button to dismiss the dialog. 9 On the Plots, click the Plot button, and view the plot. AMDS User s Guide 143

4 Example: A Patch Antenna Figure 111 Editing the Plot Parameters 144 AMDS User s Guide

Example: A Patch Antenna 4 Figure 112 Graph of S11 Shows Good Agreement with the Data in the Reference This example is based on the paper "Applications of the Three Dimensional Finite Difference Time Domain Method to the Analysis of Planar Microstrip Circuits" by Sheen et al in the July 1990 issue of IEEE Transactions on Microwave Theory and Techniques, pp 849-856. Measured results of S 11 are included in the paper and confirm the accuracy of the above results. AMDS User s Guide 145

4 Example: A Patch Antenna Example: Adding Calibration to the Patch Antenna This example calibration is an addition to the Patch Antenna example. For the calibration to work properly, the microstrip that feeds the patch antenna has to be made longer in order to create enough distance between the non-calibrated feed and the voltage line/current contour of the calibrated port. A rule of thumb is that the distance between the non-calibrated feed and the voltage line/current contour should be about 2 or 3 times the width of the microstrip. The data file(s) for this example are available from the EEsof Knowledge Center under the AMDS downloads, antenna.zip. For more information on downloading the example data file(s), refer to Data Files for Examples on page 8. Constructing the Geometry 1 Reopen the project named patch.fdtd created in the previous patch antenna example. 2 Resave the project as CalibratedPatch.fdtd and the geometry as CalibratedPatch.id. 3 Right-click the Substrate in the Object tree and choose Edit/Transform Operations > Edit Parameters. 146 AMDS User s Guide

Example: A Patch Antenna 4 4 In the Block dialog box, enter the values shown below. AMDS User s Guide 147

4 Example: A Patch Antenna 5 Click the sign in front of the Patch object. Do the same for the Substraction object inside the Patch object. 6 Right-click the object Patch and choose Edit/Transform Operations > Edit Parameters. Enter the values shown below and click Apply > Close. 148 AMDS User s Guide

Example: A Patch Antenna 4 7 Right-click the object feed and choose Edit/Transform Operations > Edit Parameters. Enter the values shown below and click Apply > Close. AMDS User s Guide 149

4 Example: A Patch Antenna 8 The resulting geometry should look like the one shown below. 150 AMDS User s Guide

Example: A Patch Antenna 4 Generating the mesh 1 Select Geometry > Adaptive Mesh Regions. 2 Select the Y directed Adaptive Mesh Region from 0.5 cm to 0.625 cm. AMDS User s Guide 151

4 Example: A Patch Antenna 3 Change the Start value to 0.1 cm and the Stop value to 0.225 cm. Click Update. 4 Select Geometry > Mesh and click Generate Mesh. 152 AMDS User s Guide

Example: A Patch Antenna 4 Adding the Feed and Calibration 1 Select Run Parameters > Components/Ports and click Delete All Components. 2 Select Geometry > View. In Mesh mode, click the ZX plane and go to slice 32. Zoom in on the region around the feed wire. AMDS User s Guide 153

4 Example: A Patch Antenna 3 Click the Feed Tool button. Right-click on the lowest part of the feed wire. Click Add a default feed. Select Run Parameters > Components/Ports, ensure that the internal impedance of this feed is set to 50 Ohms and the Batch simulation all feeds flag is checked. 154 AMDS User s Guide

Example: A Patch Antenna 4 AMDS User s Guide 155

4 Example: A Patch Antenna 4 Click the Calibration Tool button. In the ZX plane Go to slice 32, right-click the feed and select the port. 156 AMDS User s Guide

Example: A Patch Antenna 4 5 While still in the ZX plane, go to slice 41 (about 4mm away from the feed). Right-click in a cell located just above the ground plane and about the middle of the microstrip. Select Start calibrated port voltage line. AMDS User s Guide 157

4 Example: A Patch Antenna 6 Draw a voltage line from the ground plane to the microstrip. Right-click when the arrow of the voltage line touches the strip and select End calibrated voltage line. 158 AMDS User s Guide

Example: A Patch Antenna 4 AMDS User s Guide 159

4 Example: A Patch Antenna 7 Right-click the mesh cell that is just above and just at the left of the microstrip. Select Start calibrated port current contour. 160 AMDS User s Guide

Example: A Patch Antenna 4 8 Draw a current contour around the microstrip and select End calibrated port current contour. Save the geometry and project AMDS User s Guide 161

4 Example: A Patch Antenna When saving the geometry you may receive the following error message: If this occurs right-click the current contour and select Reverse current contour. 162 AMDS User s Guide

Example: A Patch Antenna 4 Running the Simulation 1 Save the geometry and the project. 2 Select Results > Run Calculation. 3 If an Acceleware FDTD accelerator is available, check the Use Acceleware FDTD Acceleration if available checkbox. 4 Click Calculate. AMDS User s Guide 163

4 Example: A Patch Antenna Examining the results 1 Once the computation is complete, select Results > FFT with the FFT size set at 64K. Click Calculate. 2 Once FFT is finished Choose Results >Plots. 3 Select Plot vs. Frequency and add the magnitude of the s11 vs. Freq. and the Calibrated s11 vs. Freq data to Data Selected for Plotting. 4 Click the Edit Plot Parameters button. Set X Min =5, X Max = 20, Y Min = -35, and Y Max = 0. Click Apply and Close. 5 To view to S-parameters, click Plot. A display of the un-calibrated and calibrated S 11 is shown below: 164 AMDS User s Guide

Example: A Patch Antenna 4 6 The figures below show the un-calibrated and calibrated S 11 for different lengths of the feed line and for different locations of the voltage line/current contour of the calibrated port. These figures clearly prove that the calibrated results are less sensitive to the exact location of the feed and the voltage line/current contour. AMDS User s Guide 165

4 Example: A Patch Antenna Figure 113 Calibrated results 166 AMDS User s Guide

Example: A Patch Antenna 4 Figure 114 Un-calibrated results AMDS User s Guide 167

4 Example: A Patch Antenna 168 AMDS User s Guide

Agilent W2100 Antenna Modeling Design System User s Guide 5 Example: A Pyramidal Horn Constructing the Geometry 171 Creating the Mesh 177 Defining Run Parameters 179 Requesting Results 183 Running the Analysis 186 Examining the Results 187 This tutorial demonstrates how to build a pyramidal horn waveguide antenna using the horn library object. The horn geometry is an optimum gain pyramidal horn antenna (see Antenna Theory and Design by W. Stutzman and G. Thiele, John Wiley & Sons, New York, 1981, pgs 413-415). The pyramidal horn aperture dimensions are 18.46 cm by 14.55 cm with a path length of the horn apex of 33.98 cm. The horn is fed by a WR-90 waveguide with an input signal of 9.3 GHz. The theoretical gain for this antenna is 22.1 db with half-power beam widths of 12 degrees in the E-plane and 13.6 degrees in the H-plane. Agilent Technologies 169

5 Example: A Pyramidal Horn Data files for AMDS examples are available from the Agilent EEsof EDA Web site. For more information on downloading the example data file(s), refer to Data Files for Examples on page 8. 170 AMDS User s Guide

Example: A Pyramidal Horn 5 Constructing the Geometry This section describes constructing the geometry of the horn and feed. Defining the Horn and Feed In this example, a pyramidal horn is created from the horn library object. 1 Select the horn library object by clicking on the horn button. 2 Complete the dialog as shown in Figure 115. AMDS User s Guide 171

5 Example: A Pyramidal Horn Figure 115 Defining the Horn Geometry 3 Click the Add button to add your changes. 4 Click the Close button to dismiss the dialog box. The horn geometry should be displayed as shown in Figure 116. 172 AMDS User s Guide

Example: A Pyramidal Horn 5 Figure 116 Displaying the Horn Geometry A wire feed should now be defined. To define the wire feed, 1 Select the wire feed icon. 2 Complete the dialog box as shown in Figure 117. 3 Click the Add button to add your changes. 4 Click the Close button to dismiss the dialog box and add the wire to the geometry. AMDS User s Guide 173

5 Example: A Pyramidal Horn Figure 117 Defining the Feed Wire Changing the Horn Material Before creating the mesh, you will need to change the PEC material to a realistic material. To do this, you can define a new material, Copper, and give it a conductivity value. 1 On the main geometry tab, pull the material selector down and select Add Material. Figure 118 Defining a New Material 2 A dialog will appear, as shown in Figure 119. Enter Copper as the Material Name. 174 AMDS User s Guide

Example: A Pyramidal Horn 5 3 Enter a value of 5.8e7 for the Conductivity (S/m). 4 Click OK. Figure 119 Material Definition for Copper 5 Select the horn object and click the Apply Material button below the tree. This will apply the material selected in the window to the object. The horn should change color to red, signifying that it is a different material than the wire. This is shown in Figure 120. AMDS User s Guide 175

5 Example: A Pyramidal Horn Figure 120 Display of the Copper Horn 176 AMDS User s Guide

Example: A Pyramidal Horn 5 Creating the Mesh A mesh must now be created. To do this, 1 Choose the Geometry > Mesh tab. The tab in Figure 121 appears. Figure 121 Meshing the Geometry 2 A suitable cell size should be determined for this model. The frequency of interest is 9.3 GHz and a cell size of no greater than 1/10 of the excitation wavelength is recommended. Selecting a Suitable Cell Size From the relationship, AMDS User s Guide 177

5 Example: A Pyramidal Horn L max = c -------------- 10 f 3 10 8 L max = ----------------------------------- 10 9.3 10 9 = 0.322 cm cell In this example, a cell size of.161 cm will be used. This easily satisfies the maximum cell size criterion and will provide more accurate results. 1 Enter.161 in the X, Y, and Z cell size locations, then click the open lock in order to lock the cell size in place. 2 Figure 121 already has the cell size locked down. The Uniform padding radio button is used to define a mesh in terms of its boundary. Enter 40 cells and, click the Generate Mesh button and the mesh is generated. 3 Save the geometry. 178 AMDS User s Guide

Example: A Pyramidal Horn 5 Defining Run Parameters With a FDTD mesh created, the input and output should be specified. To do this, choose Geometry > View. Specifying the Input Voltage The input voltage (a source voltage and port) can be defined on the FDTD mesh directly. As the mesh is available, the Mesh Mode view should be selected (to switch to this mode, use the pull down menu at the right side of the toolbar just above the view). 1 Select the YZ view and change to slice 98 by using the slice box above the display. The wire can be seen in the YZ plane at that slice. 2 Now zoom into that part of the FDTD mesh using the zoom. There is also a pan tool to change the location of the zoom point. A view similar to Figure 122 is required. AMDS User s Guide 179

5 Example: A Pyramidal Horn Figure 122 Viewing the Wire Location in Mesh Mode 3 With this location displayed, a port is required at (98, 84, 46). Use the Component/Port icon to position a y-directed port at this location. 4 After selecting the icon and correct location, right-click and select Add Default Feed. You can check the settings by right-clicking again and selecting Edit. 5 The Components/Ports tab will be displayed as shown in Figure 123. The required information is already displayed in this tab. Make sure the component is set as y-directed and has a positive polarity. This wire and voltage source with 50 Ohm source resistance model a 50 Ohm coaxial feed exciting the waveguide. 180 AMDS User s Guide

Example: A Pyramidal Horn 5 Figure 123 Source Voltage Port Definition Specifying the Voltage Waveform The next step involves defining the voltage waveform. To do this, 1 Select the Waveform tab to move to the waveform definition menu shown in Figure 124. 2 Select Automatic Convergence; however, set the Convergence Threshold level to -40dB. AMDS User s Guide 181

5 Example: A Pyramidal Horn Figure 124 Source Voltage Waveform 3 Set the waveform to Sinusoid as shown in Figure 124. This provides a single frequency simulation. 4 Enter the frequency as 9.3 GHz. Note the default units are GHz and may be changed in preferences. Use the Automatic Convergence settings. 182 AMDS User s Guide

Example: A Pyramidal Horn 5 Requesting Results This section describes how to request results for the horn antenna. Specifying Near Field Points A near-field point will be will be saved so that the fields behind the horn antenna may be viewed (with respect to time). This provides observation points to verify that the solution has converged. Convergence is assumed when the fields at these points vary with a sinusoidal waveform of constant amplitude. To set these points, 1 Choose the Geometry > View tab. 2 Select YZ slice 98 of the geometry and right-click on the location (98, 65, 6). 3 Choose the Save Data > near-zone menu item to access the Save Near-Zone Data tab as shown in Figure 125. 4 Save the Ex, Ey and Ez fields by individually selecting their respective radio buttons and clicking the Add Point button. AMDS User s Guide 183

5 Example: A Pyramidal Horn Figure 125 Saving Near-Field Point Specifying a Field Snapshot Sequence A field snapshot sequence, on a specific plane, will be saved as snapshots during the analysis. To save this transient field sequence, 1 Choose the Geometry > View tab. 2 Select YZ slice 98 of the geometry and right-click anywhere in the view. 3 Select the Save Data > Fields Snapshots menu item to go to the Save Field Snapshot tab as shown in Figure 126. 4 Define the sequence as shown in Figure 126. Note that the first snap shot will be saved after 50 time steps. Following this, every 50th time step will be saved up to 10000 time steps. 184 AMDS User s Guide

Example: A Pyramidal Horn 5 Figure 126 Specifying the Field Snapshots Sequence 5 Save the geometry and the project. AMDS User s Guide 185

5 Example: A Pyramidal Horn Running the Analysis Before running the analysis, 1 Ensure that you have saved the geometry and the project. 2 Choose Results > Run Calculation. 3 Click the Calculate button to start the calculation. 186 AMDS User s Guide

Example: A Pyramidal Horn 5 Examining the Results This section describes how to examine the results. Checking for Convergence Although automatic convergence has been selected, it is still good practice to observe that the calculation has converged. To plot the voltages at the port, 1 Choose the Results > Plots tab. 2 Add the voltage vs. time data to the Data Selected for Plotting. The plot is shown in Figure 127. By adjusting the range of the time displayed, you can see the source voltage has reached a steady-state sinusoidal waveform. AMDS User s Guide 187

5 Example: A Pyramidal Horn Figure 127 Voltage vs. Time 3 Repeat the procedure for each of the Ex, Ey and Ez components at the near field point to confirm convergence. 188 AMDS User s Guide

Example: A Pyramidal Horn 5 View Field Snapshot Sequence From the geometry window, 1 Click the Field Controls button to bring up the Field Controls window. 2 Expand Field Snapshot Sequence and double-click on the sequence shown which will allow viewing of the sequence by operating the controls. 3 The data can be viewed in several different modes which are selected in the Field Controls window. The normal mode is shown in Figure 128. To unload the fields display, double-click on the sequence in the Field Controls window. Figure 128 Viewing the Field Snapshots Sequence AMDS User s Guide 189

5 Example: A Pyramidal Horn Calculate and View the Far Field Pattern To view the 3D antenna pattern of the horn, 1 Choose the Results > Far Zone tab. 2 Select 3-D Far-Zone Pattern and select 5 degree increments in both Theta and Phi with Theta going from -180 degrees to 180 degrees and Phi from 0 to 360. 3 Click Add to place this computation in the lower window as shown in Figure 129. 4 Click Calculate to evaluate the pattern. A progress bar is displayed to show how far the calculation has progressed. 5 Return to the Geometry window and click the Field Controls button to bring up the Field Controls window. 6 Expand Far-Zone Fields and double-click on the Far Zone Plot. A display similar to Figure 130 appears. Figure 129 Computing 3-D Far-Zone Pattern 190 AMDS User s Guide

Example: A Pyramidal Horn 5 Figure 130 Display of 3-D Far-Zone Pattern To view the far field radiation/gain pattern as a 2-D slice, 1 Select Results > Far Zone. 2 Delete the existing 3D pattern data from the list (the data is saved in a.uan file). 3 Set the angular sampling and limits to those shown in Figure 131. 4 Click the Add button to add your changes. 5 Click Calculate to start the computation. AMDS User s Guide 191

5 Example: A Pyramidal Horn Figure 131 Calculating the Far Field Pattern 6 Once the computation is complete, choose Results > Plots. 7 Select the Plot vs. Angle option and add the E Theta Gain pattern data (i.e. select the E theta radio button) to the Data Selected For Plotting as shown in Figure 132. Note that the theta polarization should be chosen. 192 AMDS User s Guide

Example: A Pyramidal Horn 5 C:\Application_files\Local_Examples\AMDS\examples\Horn\horn.fdtd Figure 132 Selecting the Data for Plotting 8 Click the Edit Plot Parameters button. 9 Select the Polar option in the Plot Parameters dialog box as shown in Figure 133. AMDS User s Guide 193

5 Example: A Pyramidal Horn Figure 133 Specifying the Polar Options for Plotting Results 10 Click the Apply button to add the changes then click Close. 11 To view the polar display of the far field pattern, click Plot. A display of the far field pattern is shown in Figure 134. 194 AMDS User s Guide

Example: A Pyramidal Horn 5 Figure 134 Polar Display of Far Field Pattern AMDS User s Guide 195

5 Example: A Pyramidal Horn 196 AMDS User s Guide

Agilent W2100 Antenna Modeling Design System User s Guide 6 Static Analysis Constructing the Geometry 198 Creating the Mesh 204 Defining the Requested Output 210 Running the Analysis 212 Examining the Results 213 This example describes how to use the static analysis option in AMDS. The example also illustrates the use of thin shelling an object. Agilent Technologies 197

6 Static Analysis Constructing the Geometry A square cross section concentric capacitor will be created from a block. 1 Construct the block as shown in Figure 135. Figure 135 Block - Basis of Geometry The model should be as shown in Figure 136. 198 AMDS User s Guide

Static Analysis 6 Figure 136 Geometry of Plates 2 To cut the center out of the block, create a cutting object as shown in Figure 137. AMDS User s Guide 199

6 Static Analysis Figure 137 Cutting Object 3 Using the select object icon, select both blocks by clicking on one and using the Ctrl key to select the second. 4 When both are selected, right-click and select Boolean Operations > Subtract and subtract the Cut block from the Cap block as shown in Figure 138. 200 AMDS User s Guide

Static Analysis 6 Figure 138 Boolean Subtraction of Blocks The result is shown in Figure 139. Figure 139 Forming the Capacitor The next stage requires that the capacitor is shelled. To do this, 5 Select and right-click again on the composite object and select Solid Object Operations > Shell. The resulting menu is shown in Figure 140. AMDS User s Guide 201

6 Static Analysis Figure 140 Shelling the Capacitor 202 AMDS User s Guide

Static Analysis 6 6 As shown select and check faces 4 and 5. These will be removed from the geometry. The remaining faces will be set to a thin shell as shown in Figure 141. Figure 141 Shelled Capacitor AMDS User s Guide 203

6 Static Analysis Creating the Mesh Once the geometry is defined, it must be discretized into FDTD cells. This process is called meshing and the mesh tab is displayed in Figure 142. Figure 142 The Mesh Tab To create a mesh, 1 Select a mesh size of 0.5x0.5x0.5 as shown in the Figure with uniform padding of 20 cells. 2 To generate the mesh, click the Generate Mesh button. 3 The resulting mesh can be viewed by returning to Geometry > View tab as shown in Figure 143. However, the shelling must be modified to provide the thin electrodes required. To do this, select the object in the tree and right-click. 204 AMDS User s Guide

Static Analysis 6 Figure 143 Initial Mesh 4 Select Meshing > Edit Mesh Parameters and the menu shown in Figure 144 is displayed. AMDS User s Guide 205

6 Static Analysis Figure 144 Setting the Mesh Parameters 5 Set the parameters as shown, Shell Options to Thin and Fill Options to Off. 6 Click the Apply button and then click OK. The resulting mesh model is shown in Figure 145. 206 AMDS User s Guide

Static Analysis 6 Figure 145 Thin Shelled Capacitor AMDS User s Guide 207

6 Static Analysis Defining the Static Voltages To define the static voltages, 1 Choose the Run Parameters > Component/Ports tab. Figure 146 Component/Ports Tab 2 Select the Enable Solver option in the Static Voltages section and then click the Voltage Points button as shown above in Figure 146. 3 Using FDTD cell locations, set the cell location (31,41,31) to 0V and (31,37,31) to 10V as shown in Figure 147. 208 AMDS User s Guide

Static Analysis 6 Figure 147 Static Voltage Points AMDS User s Guide 209

6 Static Analysis Defining the Requested Output To define the requested output, 1 Choose the Geometry > View tab. 2 Display the YZ Plane view as shown in Figure 148. Figure 148 The YZ Mesh Plane 3 Ensure the Mesh Mode is selected. 4 Right-click anywhere in the main view and select Save Data > Fields Snapshots. 5 Save a sequence as shown in Figure 149. Note only 2 steps are requested as a static analysis is required. 6 Repeat this for the XY plane, as shown in Figure 149. 210 AMDS User s Guide

Static Analysis 6 Figure 149 Saving Field Snapshots AMDS User s Guide 211

6 Static Analysis Running the Analysis With the geometry and the project defined, the analysis may be carried out. 1 Choose Results > Run Calculation. 2 Click the Calculate button to begin the calculation. During the analysis, the display will show the current time step and percent of the task completed. An estimate of time remaining to finish the calculation is provided. 212 AMDS User s Guide

Static Analysis 6 Examining the Results Once the analysis is completed, the results can be viewed. View Single Transient Field From the Geometry > View window, 1 Click the Field Controls button to bring up the Field Controls window. 2 Click on the branch under Individual Fields Snapshot and then double-click the first item listed. 3 A file now appears under Loaded Fields. This is the electric field in the YZ Plane. Click on this item to display the field as shown Figure 150. A similar view is available for the XY plane. AMDS User s Guide 213

6 Static Analysis Figure 150 Static Electric Field in YZ Plane 214 AMDS User s Guide

Agilent W2100 Antenna Modeling Design System User s Guide 7 Example: A Monopole Antenna on a Conducting Box Introduction 217 Constructing the Monopole Antenna 218 Running the Analysis 224 Examining the Results 225 This example demonstrates how to build a monopole antenna using solid modeling techniques. The solution of this model analysis at 1.5 GHz provides near-zone and impedance results. Agilent Technologies 215

7 Example: A Monopole Antenna on a Conducting Box Data files for AMDS examples are available from the Agilent EEsof EDA Web site. For more information on downloading the example data file(s), refer to Data Files for Examples on page 8. 216 AMDS User s Guide

Example: A Monopole Antenna on a Conducting Box 7 Introduction A wire monopole is connected to a conducting box and fed at the junction. The radiation pattern will be calculated at a frequency of 1.5 GHz. The box will be constructed with combinations of parameters for the height of the box, and the antenna s offset location in the X dimension. Projects with the various permutations can be found within the monopole_box directory structure. The 50 mm box is built with a centered antenna. AMDS User s Guide 217

7 Example: A Monopole Antenna on a Conducting Box Constructing the Monopole Antenna Begin by starting AMDS. In order to add the box and antenna to the project, 1 Choose the Geometry > View tab. 2 Click the Block button on the toolbar to display the Block creation window. 3 Enter the parameters as shown in Figure 151. Figure 151 Block Creation Window 4 With the values set, click the Add button to create the block and add it to the project. 5 Click the Close button to dismiss the window. 218 AMDS User s Guide

Example: A Monopole Antenna on a Conducting Box 7 6 Next, add the antenna. Click the Wire toolbar button to display the Wire creation window. 7 Enter the values shown in Figure 152 to create the antenna. Figure 152 Wire Creation Window 8 With the values set, click the Add button to create the wire antenna and add it to the project. 9 Click the Close button to dismiss the window. The view of the resulting geometry should match Figure 153. To create the FDTD mesh that will be used in the calculation, 1 Click on the Mesh tab. 2 Ensure the Grid Units are set to millimeters. 3 Verify that the Grid Type is set to Auto. 4 Set the cell size to 1.67 mm cubed and click the lock icon to prevent this setting from changing. AMDS User s Guide 219

7 Example: A Monopole Antenna on a Conducting Box 5 Set a 15-cell border by choosing Uniform padding in cells and enter the number 15. 6 Finally, click Generate Mesh to create the FDTD mesh. As the box and antenna are meshed, a progress will appear. Figure 153 Resulting View of the Geometry after the Box and Antenna have been Created 220 AMDS User s Guide

Example: A Monopole Antenna on a Conducting Box 7 The location of the voltage source that excites the problem space will be positioned. To do this, 1 Choose the Geometry > View tab and select Mesh Mode from the toolbar. 2 Click in the ZX planar thumbnail and switch to slice Y=19 using the Slice edit box on the toolbar. 3 Now zoom in on the geometry where the antenna meets the box. 4 Right-click on the cell edge that is perpendicular and closest to the box. This is where the source will be placed. From the menu that appears, choose Edit port. This opens the Run Parameters > Components/Ports tab. Note that all the values for location are already entered. The location should be (34,19,46), and the direction of the source should be Z-directed. Figure 154 shows the required excitation parameters, all of which are set automatically. 5 Click Add Component to save this voltage source definition and location. AMDS User s Guide 221

7 Example: A Monopole Antenna on a Conducting Box Figure 154 Components/Ports Window Showing the Near Field Source and Associated Information The waveform must be selected. To do this, 1 Click on the Waveform tab. 2 Ensure the Waveform Type is set to Gaussian. 3 Verify that the Pulse Width is set to 32. 4 Finally, set the number of time steps to 1200. To save a transient field sequence, 1 Return to the Geometry > View tab. 2 In Mesh Mode, at Y = 19 of the ZX plane, right-click and choose Save Data > Field Snapshots. This takes you to the Request Results > Save Field Snapshots window and correctly fills in the location where you clicked. 222 AMDS User s Guide

Example: A Monopole Antenna on a Conducting Box 7 3 Set the Beginning Time Step to 50, the Ending Time Step to 1200, and change the Increment to 50. This will save a snapshot of the fields every 50 time steps between time step 50 and 1200. Save the geometry and project. 1 Click the save geometry icon on the toolbar to save the geometry. 2 Then click the save project icon to save the project. AMDS User s Guide 223

7 Example: A Monopole Antenna on a Conducting Box Running the Analysis To run the calculation, 1 Choose the Results > Run Calculation tab. 2 Set the Number of Processors to the desired number. 3 Click Calculate to begin the FDTD run. Progress during the calculation will be shown in this tab. 224 AMDS User s Guide

Example: A Monopole Antenna on a Conducting Box 7 Examining the Results Once the calculation is complete, 1 Choose the Geometry > View tab. 2 Click the Field Snapshot Sequence toolbar button to view the field snapshot sequence. The Field Controls window will appear as shown in Figure 155. Figure 155 The Field Controls Window AMDS User s Guide 225

7 Example: A Monopole Antenna on a Conducting Box 3 Expand the Field Snapshot Sequence tree item, and then double-click on the entry revealed. 4 Choose to display the Ez component with a db scale increment of 16. 5 Click the Play button to begin the player. A view after 100 time steps is shown in Figure 156. Figure 156 A Field Snapshot of Ez After 100 Time Steps To plot the input impedance versus frequency at port 1, 1 Choose the Results > Plots tab. 2 Select Plot vs. Frequency, then click on the Port 1 Impedance vs. Freq entry in the Available Data Of Selected Type list. 226 AMDS User s Guide

Example: A Monopole Antenna on a Conducting Box 7 3 Click Add Selected Plot to add the Real part of the impedance, then select Imaginary. 4 Click Add Selected Plot once more. 5 Click Edit Plot Parameters in order to set the scaling and labels for the plot. 6 Enter Real for the Legend of the first data item in the list, and Imaginary for the second. 7 Set the title of the plot, and customize the labels for the axis. 8 Set the X scale to be 0.2 to 6, and the Y scale to be 1000 to 1000. 9 Turn on the legend, click Apply, and then click Close. 10 To see the graph, click the Plot button on the Plots tab. The resulting window is shown in Figure 157. AMDS User s Guide 227

7 Example: A Monopole Antenna on a Conducting Box Figure 157 Input Impedance Versus Frequency 228 AMDS User s Guide

Agilent W2100 Antenna Modeling Design System User s Guide 8 Example: A Thin Dipole Antenna Introduction 231 Constructing the Geometry 233 Defining Run Parameters 238 Requesting Results 241 Running the Analysis 242 Examining the Results 243 Agilent Technologies 229

8 Example: A Thin Dipole Antenna This example shows how a thin wire dipole antenna can be modeled. Data files for AMDS examples are available from the Agilent EEsof EDA Web site. For more information on downloading the example data file(s), refer to Data Files for Examples on page 8. 230 AMDS User s Guide

Example: A Thin Dipole Antenna 8 Introduction A natural antenna to use for an AMDS trial calculation is a thin wire dipole. This is in part due to its simplicity, and in part due to the fact that the input impedance of 73 + j42.5 Ohms for a thin wire dipole ½ wavelength long is a well known result. However, if AMDS is used to calculate the input impedance of a ½ wavelength long thin wire dipole, the result will not be in agreement with this. Why not? The reason is that the classic value of 73 + j42.5 is obtained by approximating the current distribution on the wire dipole as exactly sinusoidal. For a "real" wire dipole this will not be true. Since AMDS is solving Maxwell's equations directly, impedance results provided by AMDS will be for the actual current distribution, not the sinusoidal approximation. In order to illustrate the high accuracy of AMDS for thin wires, compare results with calculations made by the Method of Moments [1]. The Method of Moments (MoM) is considered to be a highly accurate way of calculating impedances for thin wire antennas. In section 8.5.1 of [1], results are calculated for a thin wire dipole 0.47 wavelengths long with a radius of 0.005 wavelengths using two different MoM feed methods and for different numbers of unknown current segments. As the number of unknown segments is increased, convergence to an accurate value takes place. AMDS can be used to make a similar series of calculations. The number of AMDS mesh segments used to form the wire dipole corresponds to the number of piece-wise constant basis functions N of the MoM calculation. The AMDS mesh cell size determines the wire dipole length. The thin wire capability of AMDS is used to set the wire diameter to correspond to the MoM calculations. An AMDS feed port is located at the center of the thin wire as is the MoM feed. Using this approach, the AMDS results can be compared directly with those of [1]. Some parts of Table 8.2 of [1] are included in the following table along with corresponding AMDS results. AMDS User s Guide 231

8 Example: A Thin Dipole Antenna Table 1 Dipole Input Impedance for Two Different MoM Feed Methods and AMDS for a Dipole 0.47 Wavelengths Long and 0.005 Wavelengths Radius. N MoM-Delta Gap Mom-Magnetic Frill AMDS 11 94.2 + j49.0 32.0 + j16.7 98.0 + j66.7 21 77.7 j0.8 47.1 j0.2 85.4 + j36.2 29 75.4 j6.6 57.4 j4.5 80.2 + j25.4 41 75.9 j2.4 68.0 j1.0 77.9 + j15.5 51 77.2 + j2.4 73.1 + j4.0 77.5 + j8.8 61 78.6 + j6.1 76.2 + j8.5 77.7 + j5.3 In Table 1 above, the variable N is the number of MoM current segments or the number of AMDS mesh edges forming the wire dipole. It is clear from the table that once the number of segments is about 29 or more that both the Delta-Gap Mom and AMDS results have converged to within a few Ohms of the final result. The MoM results for the frill feed converge to these results with somewhat greater number of current segments. Comparing the three sets of results it seems evident that AMDS is just as accurate for this thin dipole as the Method of Moments. AMDS provides results of impedance vs. frequency. A convenient dipole length is chosen. Choosing a length of 30 cm means the dipole will be one wavelength long at 1 GHz, and the frequency in GHz will correspond to the dipole length in wavelengths. For example, at 0.47 GHz the dipole will be 0.47 wavelengths long. Since the wavelength is 30 cm the wire radius will be 0.15 cm. For this example calculation, the 29-edge wire dipole will be chosen. The AMDS input files thindipole29.fdtd and thindipole29.id furnished on the AMDS Example CDROM correspond to this example. 232 AMDS User s Guide

Example: A Thin Dipole Antenna 8 Constructing the Geometry The first step is to make sure the modeling unit is set to the required units. To do this, 1 Choose the Geometry > View tab. The Geometry panel is shown in Figure 158. Figure 158 The Geometry Panel 2 To change the modeling units, check the box labeled Change modeling units and then set the modeling units to Centimeters. 3 Now that the modeling unit is set, add a thin wire material. Directly above the Geometry panel is the Material panel, shown in Figure 159. Figure 159 The Material Panel 4 Ensure that the Electric materials are selected. 5 Next click on the material list to pull down the list of materials, and then click Add Material. AMDS User s Guide 233

8 Example: A Thin Dipole Antenna 6 The Pick New Material window is displayed, in which an available material is selected. For this example, material two is used. 7 Next the Edit Electrical Material window appears. In this window, select the Thin Wire option for the Material Type. Then set the Wire Radius to.15 cm. 8 Also set the Material Name to Thin Wire, so that the material can be easily identified. The Edit Electrical Material window should have the same settings as shown in Figure 160. Figure 160 The Thin Wire Material with a Wire Radius of.15 cm 9 Click the OK button in the Edit Electrical Material window. The material will be added to the list of materials, and that material will become the active material. 234 AMDS User s Guide

Example: A Thin Dipole Antenna 8 A wire needs to be added to the geometry using this material. 1 In the Geometry tab, click on the Library menu and select the Wire menu item. The Wire properties window will appear from which the two endpoints of the wire and the material of the wire are set. 2 Ensure that the Units of the wire are set to Centimeters, and then set the coordinates of point 1 to (0, 0, 0) and point 2 to (0, 0, 30). 3 Also make sure that the material is set to the thin wire material defined above. 4 Set the name of the wire to Dipole. The window appears as shown in Figure 161. Figure 161 Wire Properties Window for the 30 cm Long Dipole 5 Now click the Add button, and the wire will be added to the list of objects. 6 Click Close to close the Wire properties window. AMDS User s Guide 235

8 Example: A Thin Dipole Antenna To generate the mesh, 1 Choose the Geometry > Mesh tab. 2 Since the dipole is 30 cm long, each edge will be 30 cm/29 cells = 1.0344 cm/cells. Set the Grid units to Centimeters, and then set the cell size to 1.0344 cm for each direction. 3 Once they are set, lock the cell size by clicking on the lock symbol next to the cell size. 4 To ensure that there is enough free space around the dipole, a 20 cell padding of free space will be used in each direction. Select Uniform padding in base cells and set the padding value to 20. These settings should produce a mesh that has an origin of (-20.688, -20.688, -20.688) and is 41.376 x 41.376 x 71.376 cm, or 40 x 40 x 69 cells. 5 Click the Generate Mesh button and the mesh will be generated. At this point, there are no other changes to be made to the geometry. 6 To save the geometry, choose File > Geometry > Save As. Enter an appropriate file name, such as thindipole29.id, and click the Save button. 236 AMDS User s Guide

Example: A Thin Dipole Antenna 8 Figure 162 Mesh Tab Settings Once the Mesh is Created Now that the mesh has been built, in the Geometry tab, the viewing mode has changed to Mesh Mode. The wire should be visible in the YZ planar view at slice 21 and also in the ZX planar view at slice 21. These planes can be selected by clicking on the appropriate thumbnail views, directly to the left of the main view, and then changing the slice number to 21. AMDS User s Guide 237

8 Example: A Thin Dipole Antenna Defining Run Parameters Now an excitation needs to be added to the dipole. 1 Choose the Run Parameters > Waveform tab. 2 Select the Sinusoid Waveform type and enter.47 GHz as the Frequency. 3 Leave the Far-Zone Transformation as Steady-State, and set the Number of Time Steps to 2000, as this should provide more than enough for convergence. 4 Return to the Geometry tab and ensure that the display mode is set to Mesh Mode. 5 Next click on the Source Type tab and make sure that the method of excitation is set to Discrete Sources. 6 With the thin wire displayed in either the YZ or ZX planar view at slice 21, position the mouse pointer at the center of the wire dipole, which is at location (21,21,35), as displayed at the bottom right corner of the main view. With the mouse pointer on this wire segment, right-click the mouse and click on Edit Port, see Figure 163. 238 AMDS User s Guide

Example: A Thin Dipole Antenna 8 Figure 163 YZ Planar View with the Position at Cell (21,21,35) on a Z-directed Cell Edge 7 The Run Parameters > Components/Ports tab will become active, and the cell location and direction will be automatically filled in with the coordinates displayed when Edit Port was clicked, (21,21,35) and Z-directed. Since all the parameters are correct, just click the Add Component button, and the feed will be added to the list. AMDS User s Guide 239

8 Example: A Thin Dipole Antenna Figure 164 Components/Ports Tab 240 AMDS User s Guide

Example: A Thin Dipole Antenna 8 Requesting Results The model is ready to be run. However, if desired, additional data can be saved. To save transient fields, 1 Open the Geometry tab. 2 To select the plane to be saved, the YZ plane at slice 21 for this example, right-click the mouse and select Save Data > Field Snapshots. The Save Field Snapshots tab will automatically become active with the correct plane and slice number set. 3 Set the fields to start at time step 1, end at time step 500, and increment every 10 time steps. 4 Click Add Sequence and the sequence will be added to the list of transient fields to be saved. 5 Choose File > Project > Save As. Enter an appropriate file name, such as thindipole29.fdtd, and click Save. Figure 165 Save Transient Field Snapshots Tab AMDS User s Guide 241

8 Example: A Thin Dipole Antenna Running the Analysis Now the calculation is ready to be run. 1 Choose the Results > Run Calculation tab. 2 To run the calculation, click the Calculate button. 242 AMDS User s Guide

Example: A Thin Dipole Antenna 8 Examining the Results After the calculation finishes, verify convergence by doing the following, 1 Choose the Results > Plots tab. 2 Add Port 1 V&I vs. Time (ns) to the Data Selected for Plotting. 3 Click on Plot to view the input voltage. 4 Confirm that the waveform has settled to a constant sinusoidal amplitude. 5 Choose Results > Steady State to display the impedance results. The calculated input impedance should be approximately 80.2 + j25.4. This is shown in Figure 166. AMDS User s Guide 243

8 Example: A Thin Dipole Antenna Figure 166 Steady State Tab Showing the Impedance for the Dipole Antenna To view the Fields versus time in the plane of the wire dipole, 1 Select the Geometry tab and choose Tools > Field Control Panel. 2 From this window, individual fields and field sequences can be controlled so that they display in the main view in the Geometry tab. For more information on using the Field Controls, refer to the AMDS Reference Manual. An example field sequences snapshot is shown in Figure 167. 244 AMDS User s Guide

Example: A Thin Dipole Antenna 8 Figure 167 The Fields in a Plane One additional result is the far-zone gain of the antenna. 1 Choose the Results > Far Zone Data tab. 2 To find the maximum gain, calculate a constant Theta pattern in the Theta = 90 degree plane, for Phi between 0 and 360 degrees with an increment of 5 degrees. 3 After the calculation is finished, use the Plot tab to draw the Gain with an E Theta polarization, under the Data vs. Angle plot type. The line plot indicates a gain of about 2.08 db, close to the gain of 2.14 db for a half-wave dipole with an assumed sinusoidal current distribution. This is shown in Figure 168. AMDS User s Guide 245

8 Example: A Thin Dipole Antenna Figure 168 Maximum Antenna Gain as a Polar Plot 246 AMDS User s Guide

Agilent W2100 Antenna Modeling Design System User s Guide 9 Example: SAR Calculations Validation of Specific Absorption Rate (SAR) Calculation in AMDS 248 This section demonstrates how to build an example geometry and carry out a SAR (Specific Absorption Rate) analysis. Data files for AMDS examples are available from the Agilent EEsof EDA Web site. For more information on downloading the example data file(s), refer to Data Files for Examples on page 8. Agilent Technologies 247

9 Example: SAR Calculations Validation of Specific Absorption Rate (SAR) Calculation in AMDS The IEEE document P1528/D1.2 titled "Recommended Practice for Determining the Peak Spatial-Average Specific Absorption Rate (SAR) in the Human Head from Wireless Communications Devices: Measurement Techniques," [5] sets standards for measuring the SAR generated by wireless devices. One section of this document regarding the calibration of the measurement system contains a table of reference SAR values. Here the calibration approach is simulated in AMDS for comparison of the reference SAR values. The subject under test is a flat phantom comprised of a plastic shell and a tissue-equivalent liquid. The phantom size is set in the document as 22.5x15 cm for the frequency range of 835-3000 MHz. For lower frequencies a phantom of size 0.6x0.4 wavelengths is used. The material parameters for the tissue equivalent liquid vary with frequency and are given in Table 2 on page 249. The plastic shell should have a relative permittivity less than 5 and a loss tangent less than 0.05. The plastic shell thickness is defined as 2 mm for frequencies in the 800-3000 MHz range and 6.5 mm for lower frequencies. The tissue equivalent liquid shall have a minimum depth of 15 cm. The phantom is to be exposed to the fields of an appropriately sized dipole (see Table 3 on page 250) which is spaced 15 mm from the shell/liquid interface for frequencies less than or equal to 1000 MHz and 10 mm from the interface for higher frequencies. The local SAR and 1 and 10 gram average SAR values are to be determined for the location directly above the feed of the dipole for a 1 W input power. For the AMDS simulation, a 1 mm cubical grid was selected for all simulations except 300 MHz where a 1.5 mm grid was used. The plastic shell was defined as a dielectric with a relative permittivity of 3.7 and no electrical conductivity. The phantom and shell were sized appropriately based on the requirements of the document. The dipole antenna was 248 AMDS User s Guide

Example: SAR Calculations 9 defined as two cylinders of the specified radius with a single FDTD cell space between them for the feed. The solid view of the AMDS geometry is shown in Figure 169 on page 251, while Figure 170 on page 252 shows the actual mesh used in the calculation. The applied excitation was a voltage source with a sinusoidal input. All calculations were run for 16 full-amplitude cycles of the sine wave. Following the simulation, the input power was adjusted from the computed value to the specified 1 W. The resulting values are shown in Table 4 on page 250 compared to the reference values in the P1528 document [5]. Images of the Local SAR, 1 g Averaged SAR, and 10 g Averaged SAR in the first plane of the liquid (with the shell hidden) for the 1800 MHz case are shown in Figure 171 on page 253, Figure 172 on page 254, and Figure 173 on page 255. Table 2 Tissue-equivalent Liquid Parameters Frequency (MHz) Relative Permittivity Electrical Conductivity 300 45.3 0.87 450 43.5 0.87 835 41.5 0.90 900 41.5 0.97 1450 40.5 1.20 1800-2000 40.0 1.40 2450 39.2 1.80 3000 38.5 2.40 AMDS User s Guide 249

9 Example: SAR Calculations Table 3 Dipole Antenna Dimensions Frequency (MHz) Length (mm) Diameter (mm) 300 396.0 6.0 450 270.0 6.0 835 161.0 3.6 900 149.0 3.6 1450 89.1 3.6 1800 72.0 3.6 1900 68.0 3.6 2000 64.5 3.6 2450 51.5 3.6 3000 41.5 3.6 Table 4 Comparison of Reference and Computed (with AMDS) SAR Results for the Flat Phantom Test Object Frequency (MHz) Reference Peak 1g SAR AMDS Peak 1g SAR Reference Peak 10g SAR AMDS Peak 10g SAR Reference Local SAR AMDS Local SAR 300 3.0 3.1 2.0 2.1 4.4 4.5 450 4.9 4.9 3.3 3.2 7.2 7.4 835 9.5 9.2 6.2 5.9 14.1 14.1 900 10.8 10.5 6.9 6.6 16.4 16.3 1450 29.0 28.0 16.0 15.2 50.2 50.5 1800 38.1 36.0 19.8 18.4 69.5 68.3 1900 39.7 37.8 20.5 19.1 72.1 71.4 2000 41.1 39.7 21.1 19.9 74.6 75.1 2450 52.4 52.4 24.0 23.3 104.2 109.9 3000 63.8 61.6 25.7 23.8 140.2 150.0 250 AMDS User s Guide

Example: SAR Calculations 9 Figure 169 Example Geometry of Flat Phantom with Dipole Shown in Solid Mode in AMDS AMDS User s Guide 251

9 Example: SAR Calculations Figure 170 Example Geometry of Flat Phantom with Dipole Shown in Mesh Mode (Actual Geometry used in the FDTD calculation) 252 AMDS User s Guide

Example: SAR Calculations 9 Figure 171 Local SAR Fields Displayed in the First Layer of the Flat Phantom. Here the Display of the Shell has been Turned Off. AMDS User s Guide 253

9 Example: SAR Calculations Figure 172 1g Averaged SAR Fields in the First Slice of the Flat Phantom. Here the Display of the Shell has been Turned Off. 254 AMDS User s Guide

Example: SAR Calculations 9 Figure 173 10g Averaged SAR Fields in the First Slice of the Flat Phantom. Here the Display of the Shell has been Turned Off. AMDS User s Guide 255

9 Example: SAR Calculations 256 AMDS User s Guide

Agilent W2100 Antenna Modeling Design System User s Guide 10 Example: Calculating Antenna Diversity Parameters Importing the Geometry, Hierarchy and Materials 259 Meshing the Geometry 267 Creation of the Feeds 274 Setting the Waveform 276 Running the simulation with Monopole 1 active 278 Running the simulation with Monopole 2 active 280 Calculating the Antenna Diversity Parameters 282 This example illustrates the analysis of antenna diversity in multiple antenna systems. The geometry comprises two monopole antennas mounted on an FR4-substrate. Agilent Technologies 257

10 Example: Calculating Antenna Diversity Parameters These antennas were designed by Orban Microwave Products, Leuven, Belgium: http://www.orbanmicrowave.com The data files for this example are available on the AMDS Examples CD in the following directory: Examples/AntennaDiversity/AntennaSystem For more information on antenna diversity parameters refer to the AMDS Reference manual. 258 AMDS User s Guide

Example: Calculating Antenna Diversity Parameters 10 Importing the Geometry, Hierarchy and Materials 1 Start AMDS. 2 Select File > Geometry > Import > CAD File from the menubar at the top of the AMDS main window. 3 This opens the Import Options window. Use the Browse button associated with the CAD File input dialog to find the step-file AntennaSystem.stp. This should be located under Examples/AntennaDiversity/AntennaSystem. NOTE The availability of the Import option window depends on how the Preferences are set for AMDS. If this window is not present, select Edit > Preferences > Interface from the AMDS main menu and un-check "Skip CAD Import window when importing CAD files". AMDS User s Guide 259

10 Example: Calculating Antenna Diversity Parameters In total, 32 objects should be imported. Click OK in the Colors Assigned... dialog box when it appears. Click Import to complete the process. 4 Select Geometry > View. You should see a list of all imported objects in the Object Tree on the left side of the Geometry window. 260 AMDS User s Guide

Example: Calculating Antenna Diversity Parameters 10 5 Next, all objects should be re-arranged all the material parameters assigned. Right-click AntennaSystem in the object tree and select Group Operations > Import Hierarchy And Materials. AMDS User s Guide 261

10 Example: Calculating Antenna Diversity Parameters 6 This opens a dialog used to locate the hierarch file. Locate AntennaSystem.hchy under Examples/AntennaDiversity/AntennaSystem. Click Open. 262 AMDS User s Guide

Example: Calculating Antenna Diversity Parameters 10 This re-arranges the objects and assigns the material properties, as shown in the next figure. AMDS User s Guide 263

10 Example: Calculating Antenna Diversity Parameters To view the material properties, select the material from the Material section of the Geometry > View window and right-click it. This brings up a dialog enabling you to Edit or Delete the material. Select Edit to view the material properties. 264 AMDS User s Guide

Example: Calculating Antenna Diversity Parameters 10 There are three different materials in all: copper, teflon, and FR4. The material parameters associated with these materials can be seen in the following illustrations: AMDS User s Guide 265

10 Example: Calculating Antenna Diversity Parameters 266 AMDS User s Guide

Example: Calculating Antenna Diversity Parameters 10 Meshing the Geometry 1 Select Geometry > Mesh, fill in a base cell size of 0.5mm in all directions and set a uniform padding of 20 cells. 2 Set up an adaptive mesh for the substrate of the PCB. Select Geometry > View from the main menu, right-click Substrate PCB and select Meshing > Edit Mesh Parameters. AMDS User s Guide 267

10 Example: Calculating Antenna Diversity Parameters 268 AMDS User s Guide

Example: Calculating Antenna Diversity Parameters 10 This opens the Edit Mesh Parameters window. 3 Select the Adaptive Mesh Properties tab and specify a target cell size of 0.271mm for the lower and upper Z adaptive mesh region. Click Apply To All Regions and OK. 4 Select the Geometry > Adaptive Mesh Regions from the main menu, you should see the following display. AMDS User s Guide 269

10 Example: Calculating Antenna Diversity Parameters 270 AMDS User s Guide

Example: Calculating Antenna Diversity Parameters 10 5 To generate the mesh select Geometry > Mesh. When looking at the mesh using the Geometry > View tab, notice that all metallizations are one cell thick. This is because the metallizations are 3D objects with a thickness that is much smaller than the base cell size of 0.5 mm. Because of this, they should actually be meshed as 2D objects. This will be accomplished by forcing AMDS to mesh all metallizations as 2D objects. 6 Right-click on Monopole 1 and go to Meshing > Edit Mesh Parameters. AMDS User s Guide 271

10 Example: Calculating Antenna Diversity Parameters Set the Mesh Parameters as shown below. 7 Repeat this procedure for Monopole 2, Feedlines, and Ground. 8 Re-generate the mesh; all metallizations are now meshed as 2D objects. 272 AMDS User s Guide

Example: Calculating Antenna Diversity Parameters 10 AMDS User s Guide 273

10 Example: Calculating Antenna Diversity Parameters Creation of the Feeds 1 In Mesh mode select Geometry > View, go to slice 161 in the ZX Plane (i.e., Y=10.0). In this slice, you should be able to see the beginning of both feed lines. 2 Zoom in on the lowest feed line. Use the Mesh Editing tool to open the Edit Meshing dialog and create a feed wire from the ground to the feed line. 274 AMDS User s Guide

Example: Calculating Antenna Diversity Parameters 10 3 Click Start Edit, then use the button to set the Z-directed components. With the left mouse button pressed, draw a rectangle around the region where you want the feed wire. Enter Wire 1 in the Description region. Click Finish. 4 Click the Feed Tool button. Add a default feed at the bottom of Wire 1. Ensure that the feed found in Run Parameters > Components/Ports is Z-directed at (54,161,22). 5 Repeat the procedure for the second feed line. This should be a Z-directed at (94,161,22). 6 Save the geometry as AntennaSystem.id and the project as AntennaSystem.fdtd, respectively. AMDS User s Guide 275

10 Example: Calculating Antenna Diversity Parameters Setting the Waveform 1 A broadband analysis would show that both antennas resonate at about 1.75 GHz. Therefore, we will look at the antenna diversity parameters for this frequency. 2 Select Run Parameters > Waveform, choose Sinusoid with a Waveform Frequency of 1.75 GHz. Ensure that the Far-Zone Transformation dropdown menu is set to Steady-State. 3 Set the Simulation termination criterion to Automatic Convergence with a Convergence Threshold of -30 db. 276 AMDS User s Guide

Example: Calculating Antenna Diversity Parameters 10 4 Click Advanced and set the Maximum calculation duration to 50000 timesteps. AMDS User s Guide 277

10 Example: Calculating Antenna Diversity Parameters Running the simulation with Monopole 1 active 1 Select Run Parameters > Components/Ports, using the dropdown menu set the flag for S-parameter/VSWR Calculation to On. Ensure that the Batch simulation all feeds flag is un-checked, set the Active Feed: to 1. 2 Save the project as AntennaSystem1.fdtd. 3 Select Request Results > Save Far-Zone Data and add a complete 3D Far-Zone with a resolution of 3 degrees in both θ and ϕ. 278 AMDS User s Guide

Example: Calculating Antenna Diversity Parameters 10 4 Select Results > Run Calculation to start the simulation. NOTE We recommend the use of a graphics card if available. AMDS User s Guide 279

10 Example: Calculating Antenna Diversity Parameters Running the simulation with Monopole 2 active 1 Select Run Parameters > Components/Ports, using the dropdown menu set the flag for S-parameter/VSWR Calculation to On. Ensure that the Batch simulation all feeds flag is un-checked and set the Active Feed: to 2. 2 Save the project as AntennaSystem2.fdtd. 3 Under Request Results > Save Far-Zone Data, add a complete 3D Far-Zone with a resolution of 3 degrees in both θ and ϕ. 280 AMDS User s Guide

Example: Calculating Antenna Diversity Parameters 10 4 Go to Results > Run Calculation and start the simulation (use a graphics card if available). AMDS User s Guide 281

10 Example: Calculating Antenna Diversity Parameters Calculating the Antenna Diversity Parameters 1 Go to the Results > Antenna tab. 2 Click the Browse... button to select the Far-Zone Filename: in the Far-Zone File #1 section and open the Far-Zone pattern calculated with the first antenna active: AntennaSystem1_1.75GHz_Phi0to360in3_Theta0to180in3.uan 3 Click the Browse... button to select the Far-Zone Filename: in the Far-Zone File #2 section and open the Far-Zone pattern calculated with the second antenna active: AntennaSystem2_1.75GHz_Phi0to360in3_Theta0to180in3.uan 282 AMDS User s Guide

Example: Calculating Antenna Diversity Parameters 10 4 By default the antenna diversity parameters are calculated for a cross-polarization discrimination (XPD) of 0 db and a uniform probability density function. These values are shown at the bottom of the Results > Antenna dialog. AMDS User s Guide 283

10 Example: Calculating Antenna Diversity Parameters 5 Click the Edit Advanced Antenna Diversity Options button. In the Advanced Antenna Diversity Options section, fill in an XPD value of 6dB. Select a Gaussian probability density function with Theta MAX = 90 degrees, Sigma Theta = 30 degrees, Phi Max = 90 degrees, and Sigma Phi = 30 degrees. The resulting probability density function is shown in the display in the right side of the dialog. 284 AMDS User s Guide

Example: Calculating Antenna Diversity Parameters 10 6 Click on OK. The updated antenna diversity parameters are shown in the display at the bottom of the Results > Antenna dialog. AMDS User s Guide 285

10 Example: Calculating Antenna Diversity Parameters 286 AMDS User s Guide

Agilent W2100 Antenna Modeling Design System User s Guide 11 Example: Evaluating the Hearing Aid Compatibility Introduction 288 Importing the geometry, hierarchy and materials 290 Placement of the HAC Scan Area 296 Meshing the Geometry 300 Creation of the Feeds 302 Setting the Waveform 307 Running the Simulation 309 Evaluating the HAC 310 Agilent Technologies 287

11 Example: Evaluating the Hearing Aid Compatibility Introduction This example illustrates the evaluation of the hearing aid compatibility (HAC) according to the IEEE American National Standard Methods of Measurement of Compatibility between Wireless Communications Devices and Hearing Aids (ANSI C63.19-2006). The purpose of this standard is to establish a number of categories for hearing aids and wireless devices that indicate which hearing aids are compatible with which wireless devices. The standard specifies three tests: Wireless device, RF emissions test Hearing aid RF near-field immunity test Wireless device T-coil signal test Every test assigns a category to the wireless device and/or the hearing aid. The total performance of the wireless device - hearing aid combination is then evaluated by looking at the sum of the categories obtained by the three tests. A sum of 4 indicates that the wireless device - hearing aid combination is usable. A sum of 5 indicates that the wireless device - hearing aid combination provides normal use. A sum of 6 or greater would indicate that the wireless device - hearing aid combination provides excellent performance. AMDS enables you to evaluate the Wireless device, RF emissions test. In this test, the near electric and magnetic fields generated by the wireless device are evaluated in the region controlled for use by a hearing aid. A 5cm by 5cm measurement grid is defined over which the electric and magnetic field strengths are to be measured. This grid is located 1 cm away from the wireless device's speaker or T-coil out from the phone and is parallel to the front face of the wireless device. The measurement grid is divided into nine sub-grids. In each sub-grid the maximal value for the electric and magnetic field is determined and compared to the values given in the IEEE standard. Based on this, a category is assigned to the wireless 288 AMDS User s Guide

Example: Evaluating the Hearing Aid Compatibility 11 device. However, it should be noted that the IEEE standard allows for the exclusion of three contiguous sub-grids from the measurement. The data files for this example are available on the AMDS Examples CD in the following directory: Examples/Antenna/HAC Refer to the AMDS Reference manual and to the IEEE standard for more information on evaluating hearing aid compatibility. AMDS User s Guide 289

11 Example: Evaluating the Hearing Aid Compatibility Importing the geometry, hierarchy and materials With AMDS running: 1 Select File > Geometry > Import > CAD File 2 In the Import Options window, browse to the SAT-file AMDS_PHONE_OPEN.sat under Examples/Antenna/HAC. In total, 40 objects should be imported. Click Import. 290 AMDS User s Guide

Example: Evaluating the Hearing Aid Compatibility 11 NOTE Whether or not this window appears depends on the Preferences set for AMDS. To get this window, un-check Skip CAD Import window when importing CAD files under Edit > Preferences > Interface. AMDS User s Guide 291

11 Example: Evaluating the Hearing Aid Compatibility 3 In the Object Tree under Geometry > View, you should now see a list of all imported objects. 292 AMDS User s Guide

Example: Evaluating the Hearing Aid Compatibility 11 4 All objects should now be re-arranged and all material parameters and mesh settings should be assigned. We will now use AMDS' ability to import pre-defined hierarchies and materials. Right-click AMDS_PHONE_OPEN and go to Group Operations > Import Hierarchy and Materials. AMDS User s Guide 293

11 Example: Evaluating the Hearing Aid Compatibility 5 Browse to the hierarchy file AMDS_PHONE.hchy under Examples/Antenna/HAC. Click Open. 294 AMDS User s Guide

Example: Evaluating the Hearing Aid Compatibility 11 6 Now all objects should be re-arranged correctly, all material properties assigned and all mesh settings applied. AMDS User s Guide 295

11 Example: Evaluating the Hearing Aid Compatibility Placement of the HAC Scan Area 1 Under Geometry > View, click the HAC button. 296 AMDS User s Guide

Example: Evaluating the Hearing Aid Compatibility 11 2 In the HAC dialog, enter the coordinates for the Center point of the speaker: X=0mm, Y=42mm, and Z=-115mm. Set the Resolution to 50 and click Apply. AMDS User s Guide 297

11 Example: Evaluating the Hearing Aid Compatibility 3 Set the value for Rotate around local U-axis to 65 degrees. Click the button once, then click Apply. 298 AMDS User s Guide

Example: Evaluating the Hearing Aid Compatibility 11 4 Set the value for Rotate around local W-axis to 90 degrees. Click the button once. Click Apply. AMDS User s Guide 299

11 Example: Evaluating the Hearing Aid Compatibility Meshing the Geometry 1 Under the Geometry > Mesh tab, fill in a base cell size of 1 mm in all directions and a uniform padding of 20 cells. 300 AMDS User s Guide

Example: Evaluating the Hearing Aid Compatibility 11 2 Go to Geometry > Adaptive Mesh Regions. Note that all adaptive mesh settings have been applied automatically. 3 Under Geometry > Mesh, click Generate Mesh. AMDS User s Guide 301

11 Example: Evaluating the Hearing Aid Compatibility Creation of the Feeds 1 In Mesh mode under the Geometry > View tab, go to slice 171 in the XY Plane (i.e., Z=0.3). 302 AMDS User s Guide

Example: Evaluating the Hearing Aid Compatibility 11 2 Zoom in on the feeding strips of the GSM antenna. Use the Mesh Editing tool to create a Y-directed copper feed wire from the ground to the feed line. Next, click Start Edit, then use to set the Y-directed components. Set the material to Copper 1. With the left mouse button pressed, draw a rectangle around the region where you want to have the feed wire. Enter Wire 1 in the Description region. Click Finish. AMDS User s Guide 303

11 Example: Evaluating the Hearing Aid Compatibility 304 AMDS User s Guide

Example: Evaluating the Hearing Aid Compatibility 11 3 Click the Feed Tool. Add a default feed at the top of Wire 1. Make sure under the Run Parameters > Components/Ports tab that this is a Y-directed feed at (78,54,171). AMDS User s Guide 305

11 Example: Evaluating the Hearing Aid Compatibility 306 AMDS User s Guide

Example: Evaluating the Hearing Aid Compatibility 11 Setting the Waveform 1 Under the Run Parameters > Waveform tab, specify a Sinusoid with a Waveform Frequency of 1.8 GHz. 2 Set the Simulation termination criterion to Automatic Convergence with a Convergence Threshold of -30 db. AMDS User s Guide 307

11 Example: Evaluating the Hearing Aid Compatibility 3 Click Advanced and set the Maximum Calculation Duration to 50.000 timesteps. 308 AMDS User s Guide

Example: Evaluating the Hearing Aid Compatibility 11 Running the Simulation 1 Under Run Parameters > Components/Ports, set the S-parameter/VSWR Calculation flag to On. Set the Active Feed to 1. Make sure that the Batch simulation all feeds flag is un-checked. 2 Save the geometry as AMDS_PHONE_HAC.id and the project as AMDS_PHONE_HAC.fdtd. 3 Go to Results > Run Calculation and start the simulation (use a graphics cards if available). AMDS User s Guide 309

11 Example: Evaluating the Hearing Aid Compatibility Evaluating the HAC 1 After the simulation is finished, select Results > HAC. 310 AMDS User s Guide

Example: Evaluating the Hearing Aid Compatibility 11 2 Rescale the input power to its real value. For this example, set the input power to 0.05 W. NOTE The scaled input power under the Results > HAC tab can be set separately from the scaled input power under the Results > Power/Efficiency tab AMDS User s Guide 311

11 Example: Evaluating the Hearing Aid Compatibility 3 The HAC RF Emission Test indicates that if the input power for the GSM antenna is 0.05W, this mobile phone falls into Category 2. The Category Rating Test slider allows you to see in which of the nine sub-regions of the HAC Scan Area, the RF emission test has been violated. This is indicated by a color code. Grey means that sub-region was not used for the test (re-call that three regions can be eliminated from the test), orange means that the value of the electric and/or magnetic field in that region is higher than what is allowed for that specific category. Green means that the electric and/or magnetic field in that region is lower that what is allowed for that specific category. Set the Category Rating Test consecutively to 4, 3, 2, and 1. 312 AMDS User s Guide

Example: Evaluating the Hearing Aid Compatibility 11 AMDS User s Guide 313

11 Example: Evaluating the Hearing Aid Compatibility 4 Repeat the same procedure with the AWF (Articulation Weighting Factor) flag enabled. NOTE The articulation weighting factor is used to normalize readings of interference from different sources based upon the acoustic spectral content of the interference 314 AMDS User s Guide

Example: Evaluating the Hearing Aid Compatibility 11 Viewing the Fields on the HAC Scan Area 1 AMDS enables you to see the electric and magnetic fields in the HAC Scan Area. Under Geometry > View, click the HAC button. Under Visualization, deselect show scan area, center points, and show local axis. Click Apply > Exit. 2 Under Geometry > View, click the Field Control Panel button. AMDS User s Guide 315

11 Example: Evaluating the Hearing Aid Compatibility 316 AMDS User s Guide

Example: Evaluating the Hearing Aid Compatibility 11 3 Double-click the HAC: Tangential Component Field. Set the increment to 2 and click Apply. AMDS User s Guide 317

11 Example: Evaluating the Hearing Aid Compatibility 4 Repeat the same procedure for the other field components. 318 AMDS User s Guide

Agilent W2100 Antenna Modeling Design System User s Guide 12 Additional Examples Example: The Ferrite Circulator 320 Example: The Folded Slot Antenna 323 Example: Finger Lange Coupler 325 Example: The Meander Line 327 Example: Coplanar Stripline Bandstop Filter 331 Example: Wilkinson Power Divider 333 Example: Drude Model of Plasma Sphere 337 This chapter describes additional example applications. Many of the project and Geometry files for the AMDS examples are available from the Agilent EEsof EDA Web site. For more information on downloading the example data file(s), refer to Data Files for Examples on page 8. Agilent Technologies 319

12 Additional Examples Example: The Ferrite Circulator Data files for AMDS examples are available from the Agilent EEsof EDA Web site. For more information on downloading the example data file(s), refer to Data Files for Examples on page 8. This example shows a microwave circulator that uses anisotropic magnetized ferrite to isolate one port while providing output to the other. The circulator is a microstrip design with a 12 mm radius. The ferrite has a biasing field of 300 Oe in the -z direction perpendicular to the circulator plane, and a saturation magnetization of 300 Gauss. These correspond to Larmor Precession frequency of 5.275e9 radians per second and a saturation magnetization also of 5.275e9. The ferrite damping coefficient is 1.0e-4. The three microstrip lines forming the ports are terminated with 120 Ohm resistors which approximately match the characteristic impedances of the microstrip. The circulator is excited at port 1 with a voltage pulse. Field Patterns may be seen in Figure 174. Comparing db plots of S 11, S 21 and S 31, shown in Figure 175, it can be seen that at about 6.5 GHz, S 21 is about 10 db smaller than S 31 and S 11 is matched. This is the first resonance of the circulator. A second AMDS calculation was made at a frequency of 6.5 GHz, the lowest resonance. The steady-state electric field in the ferrite shows the null at port 2 due to the interfering waves traveling around the ferrite at different velocities. 320 AMDS User s Guide

Additional Examples 12 Figure 174 Field Pattern for the Ferrite Circulator AMDS User s Guide 321

12 Additional Examples Figure 175 S Parameters vs. Frequency for the Ferrite Circulator 322 AMDS User s Guide

Additional Examples 12 Example: The Folded Slot Antenna Data files for AMDS examples are available from the Agilent EEsof EDA Web site. For more information on downloading the example data file(s), refer to Data Files for Examples on page 8. This example shows measured and calculated results for a coplanar waveguide slot antenna, given in [2]. Figure 176 Geometry of the Folded Slot Antenna AMDS User s Guide 323

12 Additional Examples AMDS has been applied to the folded slot antenna shown in Figure 176. Using the Magnetic Wall capability of AMDS, only half of the slot geometry needs to be included in the calculation. The capability of AMDS to provide S-parameter normalization to any characteristic line impedance is used for these results since the results in the paper are for a characteristic impedance of 89 Ohms. Figure 177 shows a comparison between results obtained using AMDS and measurements from the paper. Many more results can be seen by loading the AMDS project file from the AMDS Examples CD. AMDS Figure 177 S 11 vs. Frequency for Folded Slot Antenna 324 AMDS User s Guide

Additional Examples 12 Example: Finger Lange Coupler Data files for AMDS examples are available from the Agilent EEsof EDA Web site. For more information on downloading the example data file(s), refer to Data Files for Examples on page 8. Figure 178 Geometry of Finger Lange Coupler The files associated with this model show AMDS results for a 3dB Lange coupler. After loading the lange.fdtd file, the output available for display includes the time domain voltage and current at each port for the case where port 1 is fed. The S-parameters S 11, S 21, S 31, and S 41 can be viewed through the plotting menu as plots versus frequency. The port power versus frequency is also available. AMDS User s Guide 325

12 Additional Examples Figure 179 S-parameters vs. Frequency for Finger Lange Coupler 326 AMDS User s Guide

Additional Examples 12 Example: The Meander Line Data files for AMDS examples are available from the Agilent EEsof EDA Web site. For more information on downloading the example data file(s), refer to Data Files for Examples on page 8. Figure 180 Meander Line Geometry This example describes the S-parameter results for a microstrip meander line, as shown in Figure 180. The geometry and measured results are taken from [3]. The meshed meander line geometry is in the x-y plane at slice 3. This can be viewed using AMDS and going to the z=3 plane. The meander line is on a 0.49 mm thick dielectric substrate with dielectric constant 2.43. The FDTD cell size is 0.245 mm cubes so that two cells correspond to the thickness of the substrate. The electric field mesh locations on the surface of the substrate are assigned a dielectric constant of (2.43 + 1)/ 2 = 1.72 to correctly model the air/dielectric interface in the FDTD equations. The stripline width is 1.41 mm. The lengths of the "meanders" are 9.87 mm and the spacing between "meanders" is 0.94 mm. The distance AMDS User s Guide 327

12 Additional Examples from end to end of the line is 60 mm. The Liao absorbing boundary is chosen. With ample spacing to the absorbing outer boundary, a calculation space of 289 x 122 x 25 cells results. Using the Courant limit time step size, the FDTD calculation required approximately 6,000 time steps to converge. Figure 181 Detail of the Port Feed Geometry Details of the port feed geometry FDTD mesh at one end of the meander line can be seen in AMDS in the y-z planar view at slice 22 as shown in Figure 181. Use the pan and zoom tools to see the feed region in detail. The green rectangle indicates the FDTD mesh edge where the feed port is located. The simple transition from the feed port location to the wider 328 AMDS User s Guide

Additional Examples 12 stripline conductor has been observed to provide more accurate results, especially at higher frequencies. The lowest plane of mesh edges is set to perfect conductor to simulate the ground plane. This mesh geometry is an approximation to a coaxial feed or termination connected to the bottom of the ground plane with the center conductor flaring and connecting to the microstrip. For the FDTD meander line calculation both R 01 and R 02 are set at 50 Ohms, corresponding to a coaxial cable with 50 Ohm characteristic resistance. This can be viewed in the Run Parameters > Components/Ports tab. The Gaussian pulse width has been set to 50 time steps. This will converge faster than a pulse width of 32 time steps, and with the dielectric present, results at the higher frequencies that would be excited by the narrower pulse would not be accurate. As this geometry is already meshed and the project file is defined, the calculation can be run from the Results > Run Calculation tab. When the run is complete, the results can be displayed from the Results > Plots tab. AMDS AMDS User s Guide 329

12 Additional Examples Figure 182 S 21 vs. Frequency for the Meander Strip Line The result S 21 is plotted in Figure 182 and compared with measurements from [3]. The agreement is better than the calculated results given in [3] and much better than the Touchstone results also shown [3]. 330 AMDS User s Guide

Additional Examples 12 Example: Coplanar Stripline Bandstop Filter Data files for AMDS examples are available from the Agilent EEsof EDA Web site. For more information on downloading the example data file(s), refer to Data Files for Examples on page 8. Measurements and calculations for several coplanar strip line geometries appear in [4]. Figure 183 Geometry of the Stripline Bandstop Filter Here we have applied AMDS to the Bandstop Filter of Figure 13 of [4], as shown in Figure 183. Using AMDS we have obtained excellent agreement with the measured results shown in Figure 14 of [4], given here in Figure 184. In this set of example files, we have included comparison plots of the measured results and AMDS calculations. Display the AMDS results by loading the AMDS project file from the AMDS Examples CD. AMDS User s Guide 331

12 Additional Examples AMDS AMDS Figure 184 Coplanar Strip line Bandstop Filter Results 332 AMDS User s Guide

Additional Examples 12 Example: Wilkinson Power Divider Data files for AMDS examples are available from the Agilent EEsof EDA Web site. For more information on downloading the example data file(s), refer to Data Files for Examples on page 8. This example is for a strip line Wilkinson power divider. Figure 185 Geometry of the Wilkinson Power Divider The layout of the power divider can be seen in Figure 185. The FDTD cell size is.112 x.112 x.127 mm, with the total FDTD space being 160 x 197 x 12 cells. The overall dimensions of the strip line conductors are 19.94 mm or 178 cells from Port 2 to Port 3, and the overall distance from Port 1 to the far edge of conductor is 15.57 mm or 139 cells. The dielectric has permittivity 2.94 and the total dielectric thickness is 1.524 mm, with the strip line conductor sandwiched in the middle. The blue square is a 100 Ohm isolation resistor fabricated using 100 Ohms/square resistive material. AMDS User s Guide 333

12 Additional Examples Care must be taken in meshing the power divider. First the strip line planes of the FDTD space are set to conductor, while the 4 sides are terminated in Liao absorbing boundaries. The entire FDTD space is filled with dielectric except for the strip line conductor and the isolation resistor. The strip line conductor is modeled with the 2D editor, using a series of rectangles. It is meshed as one-plane thick perfect conductor. The isolation resistor is meshed using one-plane-thick lossy dielectric with permittivity of free space and conductivity of 78.74 S/meter. This is obtained using a simple sheet impedance model as the reciprocal of the product of the sheet resistance and the cell thickness. The cell thickness is set at 0.127 mm in this dimension so that 12 cells correspond exactly to the dielectric thickness. The other two cell dimensions in the plane of the conductor were chosen to allow precise alignment of the mesh edges with the conductor steps. A very important consideration is location of the mesh edges where the port sources and terminations are to be located. One approach might be to terminate the side boundaries of the FDTD mesh normal to the strip line conductor with perfect conductor planes. Then a mesh edge normal to the outer conductor plane could be used as the source location, with the strip line conductor touching it and starting one cell inside the mesh. This would correspond physically to a strip line constructed inside a metal box with all sides closed and fed by coaxial cables with the outer conductor attached to the metal box and the center conductor going through the metal box surface to feed the strip line. This feed geometry, while a reasonable approximation to a realistic strip line circuit, does not yield good FDTD results in some situations. The difficulty is that, with the FDTD calculation entirely enclosed by conductor, the only means of dissipating the energy supplied to the calculation is by dissipation in the characteristic resistors, and of course in any other lossy dielectric materials. But many devices are made entirely or almost entirely from lossless dielectric and conductor, and some of the induced energy may be at frequencies such that it is not absorbed by the characteristic resistors. This energy then "rattles" around inside the 334 AMDS User s Guide

Additional Examples 12 conducting walls of the FDTD space, greatly increasing the number of time steps needed for convergence. It is therefore desirable to have the four side walls of the FDTD strip line calculation mesh be absorbing rather than conducting. Given this consideration, a feed location that drives the strip line with voltages relative to the top or bottom conductor is desired, so that the sides of the FDTD mesh may then be set as absorbing boundaries. However, feeding from just the top or just the bottom conductor does not provide the symmetry necessary to excite the dominant field modes of the strip line. A symmetrical arrangement for exciting and terminating the strip line can be seen in the AMDS display of the geometry by viewing the y-z plane in the x=12 slice. Use zoom and translate to get a clear view of the mesh surrounding edge (12,188,7), the location of one of the ports. The medium intensity white horizontal line is the center of a strip line conductor. This conductor is several meshes wide perpendicular to the plane of this slice of the FDTD mesh. The vertical white lines are a PEC wires which connect the ports to both the upper and lower conducting surfaces. This arrangement allows the port voltage and current to be symmetrical with respect to both strip line conducting surfaces, and is used for all three ports of the strip line circuit. The procedure used for the meander line example is followed again, with the extension to a three-port circuit. The characteristic resistances at each port are set to 50 Ohms. Port 1 is fed so that S-parameters S 11, S 21 and S 31 will be determined. The Gaussian pulse is made very wide, 1024 time steps, to reduce the number of time steps needed to reach convergence. Results at higher frequencies that would be excited by a narrower pulse are not of interest. Figure 186 shows the S 11 calculation made by AMDS for the Wilkinson power divider. The Results > FFT menu was used to increase the size of the FFT used for the S-parameter calculation so that the plot over this frequency range would be smooth. AMDS User s Guide 335

12 Additional Examples Figure 186 S 11 vs. Frequency for the Wilkinson Power Divider 336 AMDS User s Guide

Additional Examples 12 Example: Drude Model of Plasma Sphere Data files for AMDS examples are available from the Agilent EEsof EDA Web site. For more information on downloading the example data file(s), refer to Data Files for Examples on page 8. Plasma materials exhibit Drude-like behavior and are easily simulated using AMDS. The plasma is described by a radian plasma frequency and a collision frequency. We choose a plasma with a plasma frequency of 28.7 GHz and a collision frequency of 2.0e10 seconds which can be converted to the complex permittivity as shown in Figure 187. Figure 187 Complex Permittivity for Plasma After some manipulation of the plasma equation, the complex permittivity can be described using the Drude model with the parameters shown in Figure 188 of static AMDS User s Guide 337

12 Additional Examples frequency permittivity = -80.29494, infinite frequency permittivity = 1.0, relaxation time = 5.0e-11 seconds, and conductivity = 14.395 S/m. Figure 188 Plasma Material Parameters The resulting RCS vs. Frequency plot is shown in Figure 189. 338 AMDS User s Guide

Additional Examples 12 Figure 189 RCS vs. Frequency for Plasma Sphere AMDS User s Guide 339

12 Additional Examples Example: A Calibrated Microstrip-fed Dipole Antenna This example illustrates the the use of calibration on a microstrip-fed dipole antenna. This antenna was designed by Orban Microwave Products, Leuven, Belgium: http://www.orbanmicrowave.com Both the calibrated and non-calibrated S 11 are given and compared to that obtained with Agilent's ADS Momentum simulator. The data file(s) for this example are available from the EEsof Knowledge Center under the AMDS downloads, antenna.zip. For more information on downloading the example data file(s), refer to Data Files for Examples on page 8. 340 AMDS User s Guide

Additional Examples 12 Creating the Geometry 1 Start AMDS. 2 Select Geometry > View. 3 Open the Material selector and choose Add Material This will open the Edit Electric Material dialog. AMDS User s Guide 341

12 Additional Examples 4 Enter the material parameters for FR4. Set the Relative Permittivity to 4.5 and the Conductivity to 0.01. Click OK. Select the Block button to open the Block dialog. Create an FR4 substrate of 51mm x 50mm x 1.6mm with upper surface at z=1.6mm. Click Add and Close. 342 AMDS User s Guide

Additional Examples 12 5 Select the Thin Rectangular Plate button to open the Thin Rectangular Plate dialog. Complete the dialog as shown below to draw the first part of the dipole antenna at the z = 0 mm plane of the FR4 substrate. Click Add and Close. AMDS User s Guide 343

12 Additional Examples 6 Repeat this procedure to draw the other parts of the dipole at the z = 0mm plane of the FR4 substrate. Complete the Thin Rectangular Plate dialogs as shown in the following illustrations. 344 AMDS User s Guide

Additional Examples 12 AMDS User s Guide 345

12 Additional Examples 7 In the same way, add two more Thin Rectangular Plates at the z = 1.6mm plane of the FR4 substrate for the Top Patch. 8 Click Close when finished. 346 AMDS User s Guide

Additional Examples 12 9 Select the Cylinder button to add a via hole with a radius of 0.5 mm at (x, y) = (27.3 mm, 3 mm). Click Add and Close when finished. AMDS User s Guide 347

12 Additional Examples 10 Select the Wire button to add a feed wire at (x, y) = (0 mm, -3 mm). Click Add and Close when finished. 348 AMDS User s Guide

Additional Examples 12 This should give the geometry shown below. AMDS User s Guide 349

12 Additional Examples Generating the Mesh 1 Select the Geometry > Mesh. Set the mesh cell sizes to ( 0.25mm, 0.25mm, 0. mm). Make sure that the lock icon is closed once the cell sizes are set. 2 Set the padding to a uniform padding of 20 cells. 3 Click Generate Mesh. 350 AMDS User s Guide

Additional Examples 12 Adding the Feed and Calibration 1 Select Geometry > View. In Mesh mode, click the YZ Plane view. Go to slice 21. Zoom-in on the region around the feed wire. AMDS User s Guide 351

12 Additional Examples 2 Click the Feed Tool. Right-click the lowest part of the feed wire. Add a default feed. Select Run Parameters > Components/Ports, ensure that the internal impedance of this feed is 50 Ohm and that the Batch simulation all feeds flag is checked. 352 AMDS User s Guide

Additional Examples 12 AMDS User s Guide 353

12 Additional Examples 354 AMDS User s Guide

Additional Examples 12 3 Click the Calibration Tool. Right-click in the Mesh and select Show help. This will bring up the help window for the calibration. From this it is seen that adding a calibration comprises three steps: a Selecting the feed that has to be calibrated. b Drawing a voltage line. c Drawing a current contour. AMDS User s Guide 355

12 Additional Examples 4 In the YZ view, go to slice 21, right-click the feed and select the port as shown below. 356 AMDS User s Guide

Additional Examples 12 5 While still in the YZ view, go to slice 45 (about 6mm away from the feed). Right-click on a cell located just above the ground plane and about the middle of the microstrip. Select Start calibrated port voltage line. AMDS User s Guide 357

12 Additional Examples 6 Draw a voltage line from the ground plane to the microstrip. Right-click when the arrow of the voltage line touches the strip and select End calibrated voltage line. 358 AMDS User s Guide

Additional Examples 12 AMDS User s Guide 359

12 Additional Examples 7 Right-click the mesh cell that is just below and to the left of the microstrip. Select Start calibrated port current contour. 360 AMDS User s Guide

Additional Examples 12 8 Draw a current contour around the microstrip. Select End calibrated port current contour. AMDS User s Guide 361

12 Additional Examples General Comments on the Calibration For the calibration algorithm to work properly, the directions of the voltage lines and current contours have to be chosen carefully. The current contours always have to be directed from the non-calibrated feed to the actual structure. The voltage line must point inwards of the current contour. This can be easily checked by going back to the Solid view and zooming in on the calibrated port. If these conditions are not met a warning is generated when saving the project. 362 AMDS User s Guide

Additional Examples 12 AMDS User s Guide 363

12 Additional Examples The direction of the voltage line and/or the current contour can be easily reversed in Mesh mode. Use the Calibration Tool and right-click on the voltage line or the current contour. Select Reverse voltage line or Reverse current contour. The current contour should always enclose the strip as tightly as possible. A rule of thumb is that the distance between the non-calibrated feed and the voltage and current contour should be about 2 or 3 times the width of the microstrip. 364 AMDS User s Guide

Additional Examples 12 Specifying the Waveform 1 Select Run Parameters > Waveform. Choose a Gaussian waveform with a pulse width of 32 time steps. 2 Choose Automatic Convergence and set the Convergence Threshold to -30 db. AMDS User s Guide 365

12 Additional Examples 3 Click Advanced and set the Maximum calculation duration to 50000 timesteps. 366 AMDS User s Guide

Additional Examples 12 Running the Simulation 1 Save the geometry as CalibratedDipole.id and the project as CalibratedDipole.fdtd. 2 Select Results > Run Calculation. 3 Check the Use Acceleware FDTD Acceleration if available. 4 Click Calculate. AMDS User s Guide 367

12 Additional Examples Examining the Results 1 Once the computation is complete, choose Results > Plot. 2 Select Plot vs. Frequency and add the magnitude of the s11 vs Freq and the Calibrated s11 vs Freq data to the Data Selected for Plotting. 3 Select the Edit Plot Parameters button. Set X Min =1, X Max = 7, Y Min = -35, and Y Max = 0. Click Apply and Close. 368 AMDS User s Guide

Additional Examples 12 4 To view to S-parameters, click Plot. A display of the un-calibrated and calibrated S11 is shown below. A comparison between the AMDS results and ADS Momentum results is also given showing the importance of calibration for this example. AMDS User s Guide 369

12 Additional Examples 370 AMDS User s Guide

Agilent W2100 Antenna Modeling Design System User s Guide 13 3D CAD Import Example - The Helicopter Importing the CAD File 372 Creating the FDTD Mesh 375 To demonstrate the AMDS 3D CAD Import capability, this example shows how to import a CAD model of an Apache helicopter into AMDS. This is a simplified model; however, it still includes sufficient detail so that the helicopter is easily recognized. Data files for AMDS examples are available from the Agilent EEsof EDA Web site. For more information on downloading the example data file(s), refer to Data Files for Examples on page 8. Agilent Technologies 371

13 3D CAD Import Example - The Helicopter Importing the CAD File With AMDS, all parameters are set after the file is imported. To import the CAD file, 1 Choose File > Geometry > Import > CAD file. The CAD Import Options window appears (see Figure 190). 2 Click the Browse button, and browse to folder containing the apache sat file. The list of objects will display all of the 34 3D objects contained in the helicopter model. When an object on the list is selected, it will be drawn with solid color in the preview view. When an object is not selected, it will be drawn translucent. A check mark beside an object signifies that it has been selected to be imported. If there are any objects that do not need to be imported, they should be left unchecked. For this example, all the objects should be checked. Selecting all the objects in the list, then clicking in one of the check boxes, will set the check mark for all the objects. 372 AMDS User s Guide

3D CAD Import Example - The Helicopter 13 Figure 190 Import Options Window 3 The helicopter file was modeled in inches so verify that the units in the Import window should be set to inches. 4 Verify that the scale is set to 1. Materials can be defined and assigned to the objects before or after importing. To do this before importing, 1 First add the materials that will be used. 2 Select the objects to which the materials will be assigned. 3 Click Apply Material and the selected material will be applied to those objects. 4 Click the Import button. The objects from the model will be added to the list of objects in the geometry (see Figure 191). AMDS User s Guide 373

13 3D CAD Import Example - The Helicopter Figure 191 The Geometry > View Tab 374 AMDS User s Guide

3D CAD Import Example - The Helicopter 13 Creating the FDTD Mesh The next step is to create the FDTD mesh. 1 Choose the Geometry > Mesh tab. Figure 192 The Geometry > Mesh Tab 2 The memory estimator on the mesh tab makes it easy to see when the mesh parameters will cause the problem to exceed the available amount of memory. For an example like this, a 20 cell border should be used. Since this is the default setting, the option labeled Automatically size the mesh should be selected. AMDS User s Guide 375