ANN Models for Coplanar Strip Line Analysis and Synthesis

Transcription

1 200 IJCSNS Intenational Jounal of Compute Science and Netwok Secuity, VOL.8 No.10, Octobe 2008 Models fo Coplana Stip Line Analysis and J.Lakshmi Naayana D.K.Si Rama Kishna D.L.Patap Reddy Chalapathi Institute of Engg & Technology, Guntu,A.P,India Vignan s Engineeing College, Vadlamudi,Guntu,A.P,India Jawahalal Nehu Technological Univesity, Hydeabad, A.P,India Summay Neual netwoks ecently gained attention as fast and flexible vehicles to micowave modeling, simulation and optimization. Afte leaning and abstacting fom micowave data, though a pocess called taining, neual netwok models ae used duing micowave design to povide instant answes to the task leaned. This pape pesents simple and accuate models fo the analysis and synthesis of CPS stuctues to vey accuately compute the chaacteistic paametes and the physical dimensions espectively fo the equied design specifications. Key wods: Neual Models, Algoithms, Coplana stip lines,analysis, 1. Intoduction The coplana stip line (CPS) consists of a dielectic substate with two paallel stip conductos sepaated by a naow gap. Micowave integated cicuits (MICs) using coplana lines have been developed as an attactive altenative to micostip based cicuits owing to the advantages of coplana waveguides (CPWs) and coplana stips (CPSs), such as easy incopoation of seies and shunt elements and uniplana featues. Howeve, the application of coplana lines (CPW, CPS) to micowave cicuit designs is not yet widespead due to the lack of adequate tools fo coplana cicuit design and optinisation. It is noted that so fa, all the conventional CAD models fo coplana lines ae analysis models whee the electical paametes ae obtained by the geometical paametes of coplana lines [l]. No closed-fom synthesis fomulas to diectly obtain the physical dimensions of coplana stuctues fo the equied design specifications ae available in the liteatue. In contast, both analysis and synthesis closed-fom fomulas fo micostip lines have existed fo a long time [2]. Its applications include balanced mixes and feed netwok wok fo pinted dipole antennas. Most of the conventional models fo vaious CPSs ae the analysis models [1,3] that have been used to detemine the chaacteistic paametes of CPS stuctues. The synthesis models wee also pesented in the liteatue[4 6]. These synthesis models ae diectly used to obtain the physical dimensions of CPS stuctues fo the equied design specifications. The model poposed by Deng et al. [4] is mathematically complex. The models pesented by Yildiz [5] and Yildiz et al. [6] ae simple but do not have vey good accuacy. Hence, they ae not vey attactive fo the CPS synthesis. epesents a pomising modeling technique, especially fo data sets having non-linea elationships that ae fequently encounteed in engineeing [7]. In the couse of developing an model, the achitectue of and the leaning algoithm [8] ae the two most impotant factos. s have many stuctues and achitectues [9]. The class of and/o achitectue selected fo a paticula model implementation depends on the poblem to be solved. Afte seveal expeiments using diffeent achitectues coupled with diffeent taining algoithms, in this pape, the multilayeed pecepton (MLP) neual netwok achitectue is used in calculating the electical paametes and physical dimensions of CPSs.Neual model fo the CPS synthesis was intoduced fo the fist time by Salivahanan et al. [10]. This neual model has some disadvantages. Fist of all, it can be used only in the naow ange. It is not possible to design CPSs having small chaacteistic impedances (Z0 < 70 Ω).Thus, this neual model is not suitable fo pactical anges. Moeove, the neual model poposed in [10] was tained using only one leaning algoithm. In this pape, simple and accuate neual models with a vey wide ange of usage fo CPS analysis and synthesis ae pesented within the following design-paamete anges: , 0.01 S/H 1.86, and 0.01 W/H These neual models wee tained with, Back Popagation (BP- MLP3), Spase Taining (ST),Conjugate Gadient(CG), Adaptive Back Popagation(ABP), Quasi-Newton (QN- MLP), Quasi-Newton(QN), Hube-Quasi-Newton (HQN),Auto Pilot (AP-MLP3) and simplex method (SM) algoithms.fo the validation of the neual models poposed in this pape, the neual analysis and synthesis esults have been compaed with the esults of the quasi-static analysis [1] and the synthesis fomulas poposed by Deng et.al [4]. Manuscipt eceived Octobe 5, 2008 Manuscipt evised Octobe 20, 2008

2 IJCSNS Intenational Jounal of Compute Science and Netwok Secuity, VOL.8 No.10, Octobe Analysis and Fomulas fo Coplana Stip lines A CPS with a finite dielectic thickness configuation is depicted in Fig. 1, whee S,W,H, and epesent the slot width, stip width, substate thickness, and elative dielectic constant of the substate mateial, espectively. All the conductos ae assumed to be infinitely thin and pefectly conducting. Owing to the inceasing populaity of coplana waveguides (CPW) and coplana stip lines (CPS) fo the design of hybid and monolithic micowave integated cicuits, it is impotant to have a set of eliable analytical fomulas fo thei quasi-tem electical paametes (chaacteistic impedance Z 0 and effective dielectic constant eff ). Fig. 1. Configuation of a CPS The following analysis fomulas poposed in [1] calculates the chaacteistic impedance Z 0 and effective dielectic constant eff given by Z 120. π K k = 0 ' eff K k While eff is given by eff ' K( k1 ) ' ( 1) (1) 1 K k = 1 + (2) 2 K k K k Whee k = a/ b; sinh π a 2H k1 = sinh πb 2H (3) K is the complete elliptic integal of the fist kind and ' 2 k = (1 k ) (4) The following synthesis fomula poposed in [4] calculates the stip width (W ) and slot width (S) fo a given substate (H, ) and equied chaacteistic impedance Z 0 by choosing an appopiate slot width (S) and stip width (W). S W = G H Z S (,,, ) ( ) 0 0 (5) S = W. G, H, Z, W (6) The fomulas given above ae valid fo the anges of, S H 10 3( 1+ ln ), W H 10 ( 1+ ln ) and Analysis and models based on s fo CPSs In this pape, thee simple and accuate neual models ae poposed fo CPS analysis and synthesis. The fist neual model computes the electical paametes (Z 0, eff ) fo a given Substate (S,W, H, ).The Second neual model computes the stip width W fo a given substate (H, ) and equied chaacteistic impedance Z 0 by choosing an appopiate slot width S. The thid neual model calculates the slot width S fo a given substate (H, ) and equied chaacteistic impedance Z 0 by choosing an appopiate stip width W. Fig. 2,Fig.3 and Fig.4 shows the fist, second and thid neual models used fo neual computation of the electic paametes, stip width and slot width of CPSs, espectively. models ae a kind of black box models, whose accuacy depends on the data pesented to it duing taining. A good collection of the taining data, i.e., data which is well-distibuted, sufficient, and accuately simulated, is the basic equiement to obtain an accuate model. Fo micowave applications, thee ae two types of data geneatos, namely measuement and simulation. The selection of a data geneato depends on the application and the availability of the data geneato. The taining and testing data sets used in this pape wee obtained fom the espective quasi-static analysis and synthesis fomulas poposed by Deng et.al [1,4] ae used fo analysis and synthesis.the design paamete anges of the CPSs in these samples ae , 0.01 S/H 1.86, 0.01 W/H 5.59, 200 μm H 1250 μm, and espective chaacteistic impedance 30Ω Z 0 150Ω. The tain and test data sets wee geneated unde the following constaints: nomalized stip width W/H 10/(1 + ln ), nomalized slot width S/H 10/[3(1 + ln )],and elative dielectic constant The aim of the taining pocess is to minimize the taining eo between the taget output and the actual output of the. Selection of taining paametes and the entie taining pocess mostly depend on expeience besides the type of poblem at hand. Afte seveal tials, it was found in this pape that one hidden layeed and thee hidden layeed netwoks wee achieved the task in high accuacy fo

3 202 IJCSNS Intenational Jounal of Compute Science and Netwok Secuity, VOL.8 No.10, Octobe 2008 analysis and synthesis. The most suitable netwok configuation found was 5 x 20 x 2 fo analysis and fo synthesis. It means that the numbes of neuons wee 5,20, and 2 fo the input laye, the hidden laye and the output laye, espectively. Pilot (MLP3) and Simplex method leaning algoithms. The taining and test eos obtained fom the fist, second and thid neual models ae given in Table 1,2 and 3. It is clea fom Table 1,2 and 3 that the esults of the neual models tained by the Hube Quasi Newton algoithm is bette fo the Analysis and Quasi Newton algoithm is bette fo of the neual models. Table 1.Taining and Test eos of Neual models fo the Analysis of CPSs Fig 2. Neual models fo CPS Analysis Algoithm Taining Eo (Coelation BP-MLP ST CG ABP QN-MLP QN HQN AP-MLP SM Fig 3. Fig.4. Neual model used to calculate the stip width of a CPS Neual model used to calculate the slot width of a CPS Table 2.Taining and Test eos of Neual models fo the of Stip width of CPSs Algoithm Taining Eo (Coelation HQN SM CG ABP QN QN-MLP ST Numeical s and Discussion s have been successfully used to compute the electical paametes, stip width o slot width of a CPS fo a given substate mateial by choosing an appopiate slot o stip width. In ode to obtain bette pefomance, faste convegence, and a simple stuctue, models wee tained with the Back popagation (MLP3), Spase Taining, Conjugate Gadient, Adaptive Back Popagation, Quasi- Newton (MLP), Quasi-Newton, Hube-Quasi-Newton,Auto Table 3.Taining and Test eos of Neual models fo the of slot width of CPSs Algoithm Taining Eo (Coelation HQN SM CG ABP QN QN-MLP ST

4 IJCSNS Intenational Jounal of Compute Science and Netwok Secuity, VOL.8 No.10, Octobe In ode to validate the neual models fo CPS analysis and synthesis, compehensive compaisons have been made. In these compaisons, the esults obtained fom the fist neual model tained by Hube Quasi Newton algoithm ae compaed with the esults of espective quasi-static analysis [1] as shown in Table 4. The esults obtained fom second and thid neual models tained by Quasi Newton algoithm ae compaed with the synthesis esults poposed by deng et.al [4] as shown in Table 5 Table 4. Compaison of Analysis s with that of s ( = , S= ) H ( μm) S/S+2W Z 0 (Ω) Analysis Table 5. Compaison of s with that of s ( =25.2,H=725) Z 0 (Ω) S ( μm) W( μm) Z 0 (Ω) W ( μm) S ( μm) Conclusion Accuate and simple neual models ae pesented to compute the physical dimensions of CPSs fo the equied design specifications. These models have been developed by taining the neual netwok with the numeical esults of quasi-static analysis in the equied anges of model input vaiables. It was shown that the esults of the neual models tained by the Hube Quasi Newton algoithm and Quasi Newton algoithms ae bette fo analysis and synthesis of CPSs. The neual esults have also been compaed with the esults of the espective quasi-static analysis and the synthesis fomulas available in the liteatue. Refeences [1] Ghione. G. and C. Naldi, Analytical fomulas fo coplana lines in hybid and monolithic MICs, Electonic Lettes, Vol. 20, , [2] Whelle, H.A.: Tansmission-line popeties of Paallel stips sepaated by a dielectic sheet, IEEE.Tans. 1965, MTT-13, pp [3] Kno, J. B. and K. D. Kuchle, Analysis of coupled slots and coplana stips on dielectic substate, IEEE Tanactions on Micowave Theoy and Techniques, Vol. 23, , [4] Deng, T. Q., M. S. Leong, P. S. Kooi, and T. S. Yeo, fomulas fo coplana lines in hybid and monolithic MICs, Electonic Lettes, Vol. 32, , [5] Yildiz, C., New and vey simple synthesis fomulas fo coplana stip line, Micowave and Optical Technology Lettes, Vol. 44, , [6] Yildiz, C., A. Akdagli, and M. Tukmen, Simple and accuate synthesis fomulas obtained by using a diffeential evolution algoithm fo coplana stip lines, Micowave and Optical Technology Lettes, Vol. 48, , [7] [7] Haykin, S., Neual Netwoks: A Compehensive foundation, Macmillan College Publishing Comp.,NewYok,USA,1994. [8] J.L. Naayana, D.K.Si Rama Kishna and D.L.Patap Reddy, Neual Netwok Taining Algoithms fo RF and Micowave Applications, Intenational Confeence on Advanced Computing and Communication Technologies, Hayana, , 2007 [9] J.L.Naayana, D.K.Si Rama Kishna and D.L.Patap Reddy, Stuctues fo RF and Micowave Applications, Intenational Confeence on Recent Applications of Soft Computing in Engineeing And Technology, Alwa, 91-98, 2007 [10] Salivahanan, S., R. Ramesh, S. Kathikeyan, S. Raju, and V. Abhaikuma, Atificial neual netwok models fo coplana stip line synthesis, IETE Jounal of Education, Vol. 43, 27 31, 2002.

5 204 IJCSNS Intenational Jounal of Compute Science and Netwok Secuity, VOL.8 No.10, Octobe 2008 of IETE and IE ()I). D. K.Si Rama Kishna is woking as Pofesso of E.C.E Dept. and Dean (R&D), Vignan s Engg. College, Vadlamudi, Guntu. He Completed his doctoal degee in the yea 2001 fom Andha Univesity, Vizag His aeas of inteest include Micowaves, Neual Netwoks, Wavelet Tansfoms, Genetic algoithms, Evolvable Computing, Image Pocessing, Signal Pocessing. He Published 25 papes in Intenational confeences and Jounals. He is a fellow J.Lakshmi Naayana is woking as Assistant Pofesso, E.C.E Dept., Chalapathi Institute of Engineeing and Technology, Guntu, and he is eseach schola in E.C.E Depatment., JNTU, Hydeabad. His aeas of inteest include Micowaves, Neual Netwoks, Antennas,Signal Pocessing and Wavelet Tansfoms.He Published 12 papes in intenational confeences and Jounals. He is a Membe of IETE and IE (I). D.L.Patap Reddy is woking as Pofesso & Head in ECE Dept., JNT Univesity,Hydeabad. He completed his doctoal degee in the yea 2001 fom J.N.T.U Hydeabad..His cuent activity in eseach and development includes, apat fom telecommunication engineeing subjects, Image Pocessing, Patten Recognition and Linguistic pocessing of Telugu language. He published 25 technical papes, aticles and epots.he is active membe in pofessional bodies like ISTE,IE,IETE and CSI.