Simulation Advances for RF, Microwave and Antenna Applications Bill McGinn Application Engineer 1
Overview Advanced Integrated Solver Technologies Finite Arrays with Domain Decomposition Hybrid solving: FEBI, IE Regions Physical Optics Solver in HFSS-IE Transient Finite Elements in HFSS New layout interface for HFSS: Solver on Demand in Designer Usability Enhancement Radiated fields.. Network installation improvements 3D modeler improvements CAD Integration in Workbench Improved Multiphysics flow 2
Advanced Solvers: Finite Arrays with DDM 3
Finite Arrays with Domain Decomposition Efficient solution for repeating geometries (array) with domain decomposition technique (DDM) 4
A Review: Domain Decomposition Distributed memory parallel solver technique Distributes mesh sub-domains to network of processors Significantly increases simulation capacity Highly scalable to large numbers of processors Automatic generation of domains by mesh partitioning User friendly Load balance Hybrid iterative & direct solver Multi-frontal direct solver for each subdomain Sub-domains exchange information iteratively via Robin s transmission conditions (RTC) Distributes mesh sub-domains to networked processors and memory 5
Finite Arrays Solve large finite array designs Efficient setup and solution Define unit cell and array dimensions Efficient geometry creation and representation Efficient Domain Decomposition solution Leverages repeating nature of array geometries Only mesh unit cell Virtually repeat mesh throughout array Post-process full S-parameter Couplings included Edge effects included 3D field visualization Far field patterns for full array Memory efficient Enabled with the HFSS HPC product 6
Finite Arrays by Domain Decomposition Each element in array treated as solution domain One compute engine can solve multiple elements/domains in series Distributes element sub-domains to networked processors and memory 7
Example: Skewed Waveguide Array 16X16 (256 elements and excitations) Skewed Rectangular Waveguide (WR90) Array 1.3M Matrix Size Using 8 cores 3 hrs. solution time 0.4GB Memory total Using 16 cores 2 hrs. solution time 0.8GB Memory total Additional Cores Faster solution time More memory. Unit cell shown with wireframe view of virtual array 8
Skewed Waveguide Array Patterns from 8X8 Array Dashed is idealized infinite array analysis Solid from finite array analysis Two simulations use identical mesh Note edge effects due to finite array size 9
Running Finite Array Use Master/Slave unit cell design to adapt the mesh Called Unit Cell for Adaptive Meshing in image Copy/Paste Design Called 8X8 Array in image Create a single pass setup in finite array design On Advanced tab use Setup Link to link mesh from unit cell design Doing adaptive meshing in finite array design will be time consuming and not as efficient 10
Efficient: 8X8 Array Patch Array Direct solver with 12 cores 5:05:14 60.8 GB RAM Finite Array DDM with 12 cores 00:44:53 1.8 GB 6.8X faster 33.8X less memory 11
HPC: Faster with additional cores Linux cluster 16X Dell PowerEdge R610 Dual six-core Xeon X5760, 8GB per core Same 8X8 array of probe feed patch antennas 3M+ matrix size, 64 excitations Study performed using 101, 51,26, 11, 6 and 3 engines.* 101 simulation time = 17 min., 20X faster than direct solver *Three engines used as baseline 12
Hybrid Solving: Finite Element- Boundary Integral 14
Finite Element-Boundary Integral Solving Larger Problems with Rigor Antenna Placement Study: UHF Antenna on Apache UH64 airframe Finite Elements with DDM Boundary Integral (3D Method of Moments) Hybrid Finite Element-Boundary Integral (FE-BI) 15
Hybrid Solving: Finite Element- Boundary Integral Apache helicopter UHF antenna placement study @ 900 MHz Solution volume 1,250 m 3 33,750 λ 3 Solution Specs 72 engines Matrix size = 47M 6 adaptive passes 300 GB RAM 5 hr 30 min Finite Elements with DDM 16
Hybrid Solving: Finite Element- Boundary Integral Apache helicopter UHF antenna placement study @ 900 MHz Solution surface 173 m 2 1557 λ 2 Solution Specs 12 core MP 680k unknowns 9 adaptive passes 83 GB RAM 5 hr 28 min Boundary Integral, 3D MoM with HFSS-IE 17
Hybrid Solving: Finite Element- Boundary Integral Apache helicopter UHF antenna placement study @ 900 MHz FEM solution volume 69 m 3 1863 λ 3 IE solution surface 236 m 2 2124 λ 2 Solution Specs 12 cores total using DDM with MP Matrix Size = 2.9M 6 adaptive passes 21 GB RAM 1 hr 3 min Hybrid Finite Element Boundary Integral Compared to 72 core FEM solution 14X less memory, 5.5 times faster 18
Hybrid Finite Element-Integral Equation Method Finite Element Based Method HFSS Efficient handle complex material and geometries Volume based mesh and field solutions Airbox required to model free space radiation Conformal radiation volume with Integral Equations Integral Equation Based Method HFSS-IE Efficient solution technique for open radiation and scattering Surface only mesh and current solution Airbox not needed to model free space radiation This Finite Element-Boundary Integral hybrid method leverages the advantages of both Finite methods Elements to achieve vs. Integral the most Equations accurate and robust solution for radiating and scattering problems 19
Summary of FEBI performance Type Time, Ratio Memory, Ratio FEM + DDM 5hr 30min, 1 300GB, 1 IE 5hr 28min, 1 83GB, 3.6 FEBI 1hr 3min, 5.5 21 GB, 14.3 20
HFSS Hybrid Solving Hybrid Solving introduced in HFSS 13 with FEBI A highly accurate solution for open boundary problems Accurate: Solves directly for equivalent surface currents on boundary conditions Efficient: Conformal arbitrary shape BC to reduce FEM solution domain Reflectionless: can be placed closed to radiating surface. Does not have to be continuous: provides possibility of physically separate FEM volumes 21
Example: Missile Launch 22
FE-BI and Distributed Solving Distributes mesh sub-domains to network of processors FEM volume can be subdivided into multiple domains IE Domain is distributed to second node in machine list Significantly increases simulation capacity Multi-processor nodes can be utilized HPC distributes mesh sub-domains, FEM and IE domains, to networked processors and memory 23 FEM Domain 1 FEM Domain 2 FEM Domain 3 FEM Domain 4 IE Domain
Hybrid Solving: IE Regions 24
FEBI and Physically Separate Domains Reflector with multiple FE-BI domains Conducting reflector and feed horn each surrounded by air with FEBI applied to surface of air volumes Provides integral equation link between FEM domains But the 3D MoM solution from integral equations could be applied directly to conducting surface only 1meter 10λ 1meter 20λ 1meter 30λ Frequency Memory Required Frequency Memory Required Frequency Memory Required 3 GHz 2GB 6 GHz 10GB 9GHz 30GB 25
HFSS Hybrid Solving IE Regions Parallelized IE regions solved in parallel. Analogous to FEM domains Rigorous Multiple reflection Automated 26
IE Dielectric Regions Solve large homogeneous blocks of dielectric with a boundary condition Replace enclosed arbitrary dielectrics Solve with multiple open or enclosed IE regions Conducting IE regions may be inside dielectric IE regions Antenna Ground Penetrating Radar Air Surface Soil Mine FEM Enclosed IE Conducting IE Different solution domains may be solved in parallel with DDM 27
HFSS IE Regions - Example 28
Physical Optics 29
HFSS-IE PO Asymptotic solver for extremely large problems In HFSS-IE Solves electrically huge problems Currents are approximated in illuminated regions Set to zero in shadow regions No ray tracing or multiple bounces Target applications: Large reflector antennas RCS of large objects such as satellites Option in solution setup for HFSS-IE. Sourced by incident wave excitations Plane waves or linked HFSS designs as a source 30
Physical Optics (PO) Recieve Handles object scattering using asymptotically derived currents. There is an edge effect but it does not yield the true diffracted fields. Scatterer Source Currents approximated as J 2nxH inc 31
PO Solver in HFSS-IE 14 PE C Where: J PO = 2(n x H inc ) PO assumes the fields on all illuminated surface are the incident fields Effects of the scatterers are included by assuming the incident fields are scattered at each point on the body as if it were reflected from an infinite tangent plane at that point; J~2(n x H inc ) for PEC. For non-illuminated surfaces the J are set to zero. 32
PO Examples Notice the shadowing of the gun barrel on the tank and the tank on the ground. 33
HFSS-IE PO - Example Offset reflector 50 λ 0 in diameter fed by a horn HFSS far field link Simulated with 8 cores IE: 48.3min and 11.9GB PO: 23S and 286MB Note > 120x speedup 34
HFSS Transient 35
Transient problems 36
Aircraft: Pulsed RCS 37
HFSS Transient Introduced in HFSS 13.0 Discontinuous Galerkin Time Domain (DGTD) Finite element solution Retains accuracy and reliability of adapted unstructured-mesh Arbitrary Geometries Supports higher order basis functions Efficient for geometries with a wide range of geometric detail Local time stepping Based on element size, order and material property mesh elements may advance in time with different time steps Waveform Input Flexibility Oblique Angles on Incident Waves 38
HFSS Transient: New in R14 Transient Network Analysis Separate Frequency and Time domain Edit Source settings Specify delay of TDR to synchronize rise times Handling of partial S due to passive ports Transient Scaling and delay of individual sources General Support for general frequency dependent materials 39
Solver on Demand 40
Designer RF with HFSS - Solver on Demand HFSS - Solver on Demand Intuitive PCB design entry for HFSS Chips, packages, channels, modules, Designer layouts simulated with HFSS Automated boundary and port setups Finite dielectrics and ground supported Wave and Lumped Gap Port Single ended and Differential Vertical and Horizontal Coaxial, CPW and Grounded CPW 41
Design Description Balanced Amplifier MMIC amplifiers in parallel Gain = 22dB Power = 30dBm P1dB = 11dBm F=10GHz 42
Usability Enhancements 43
General Enhancements Save Radiated field data only Reduces the amount of stored data Import list for Edit Sources Can include parametric variables ~10X Reduction Network Installation for clusters Improved reliability on Linux Non-graphical solves without product-links Solves are independent of Mainwin registry Installations on Windows Non-graphical solves without product-links New Registry Configurations Installation: Lowest precedence Defaults applicable to all users Machine: Defaults applicable to all users on a machine. User : Machine independent user specific default User and machine: Highest precedence Defaults specific to user + machine 44
Save Radiated Field Data Only Reduces the amount of data stored on hard drive for large antenna problems Setting in Solution Setup, Advanced Tab: discrete and fast sweeps ~10X Reduction 45
Import List Entry for Edit Sources Easy input for magnitude and phase from source list Can include parametric variables 46
Ansoft HPC Enhancements: Network Installation on clusters Improved reliability on Linux Non-graphical batch solves without product-links Solves are independent of Mainwin registry No hung mainwin services or corrupt mainwin registry Network installations on Windows for Non-graphical batch solves without product-links Need to install VC redistributables on nodes ANSYS Registry XML file 47
Registry Configuration Software settings can be defined at various levels (all operating systems): Installation: Lowest precedence Installation level defaults applicable to all users Machine: Machine specific defaults applicable to all users on a given machine. User : Machine independent user specific default User and machine: specific value Highest precedence Most specific value: Specific to user and machine Run: UpdateRegistry -help from the product installation directory for usage details. 48
IronPython To get started using IronPython (from any Desktop Product): Set the environment variable ANSOFT_ENABLE_COMMANDWINDOW_UI=1 From the user interface: Tools>Open Command Window 49
3D Modeler Enhancements View customization. 64-bit user interface Post process larger simulations Z-stretch Speed Improvements Faster geometry loading Improved solid modeler speed. Improvements for selecting complex objects. 50
CAD Integration on WB Improvements CAD integration in ANSYS Workbench provides direct link to 3 rd party CAD tools Such as ProEngineer, Catia, SpaceClaim Added support for parametric analysis and distributed solving of CAD parameter 51
Ansoft to ANSYS Geometry Transfer Geometry and material assignment transfer from Ansoft to ANSYS Consume geometry from multiple upstream CAD sources Source can be any of CAD, DesignModeler or Ansoft products Further geometry edits are possible in ANSYS Design Modeler Creates User Defined Model (UDM) for each geometry input. 52
Conclusions Advanced Integrated Solver Technologies Physical Optics Solver in HFSS-IE New Layout interface for HFSS: Solver on Demand in Designer Usability Enhancement Improved Multiphysics flow 53