Quasi-Elliptic UWB Bandpass Filter Using Multilayer Liquid C

利用多层液态晶体高分子聚合物技术(Multilayer Liquid Crystal Polymer Technology)设计的具有椭圆响应的多层超宽带(UWB)带通滤波器,

202IEEEMICROWAVEANDWIRELESSCOMPONENTSLETTERS,VOL.20,NO.4,APRIL2010

Quasi-EllipticUWBBandpassFilterUsingMultilayerLiquidCrystalPolymerTechnology

Zhang-ChengHao,Member,IEEE,andJia-ShengHong,SeniorMember,IEEE

Abstract—Anovelultra-wideband(UWB)bandpass lter(BPF)withquasi-ellipticresponseusingnon-uniformperiodicalstructuresispresented.Inthedesign,aperiodicalunitstructureisproposedandstudied,whichcanprovidetransmissionzerosatbothlowerandupperstopbandstoimprovetheselectivity.Theproposedperiodicalunitstructureconsistsofbroadsidecou-plingpatches,slottedgroundandembeddedquarter-wavelengthresonator.Itcanbeimplementedusingamultilayerstructurewithacompactsize.AhighselectivityUWBBPFwithmultipletransmissionzeroscanbedesignedbycascadingafewproposednon-uniformperiodicalunits.Asademonstration,aUWBBPFwith veperiodicalunitsisdevelopedbyfull-wavesimulation.Multilayerliquidcrystalpolymertechnologyisusedtoimplementthedesignedprototype.Thepredictedresultsareveri edbytheexperiments,whichshowthatthefabricated lterhasanultrawidefractionalbandwidth,awidestopbandandahighselectivitywithquasi-ellipticresponse.Theproposed lterisattractiveforUWBcommunicationandradarsystems.

IndexTerms—Bandpass lter(BPF),liquidcrystalpolymer(LCP),ultrawideband(UWB).

usingnon-uniformslottedgroundstructuresarestudiedin[9],[10].

Liquidcrystalpolymertechnologyprovidesmultilayerinte-grationcapability,whichcanbeusedtoimplementcompactmultilayerthreedimensionalmicrowavecircuits.Meanwhile,LCP lmshaveexcellentelectricalandmechanicalperformancesuchassmallthermalexpansioncoef cient,lowdielectriccon-stantandlowdielectricloss.Inthisletter,weproposeanovelUWB lterusingamultilayernon-uniformperiodicalstructure.Bytakingadvantageofmultilayertopology,acompactperiod-icalunitisproposedandstudied,whichcanprovidetwotrans-missionzeroslocatedatthelowerandupperstopbands,respec-tively,toimprovetheselectivity.Aprototypeincluding veperiodicalunitsisdesignedandimplementedusingmultilayerLCPtechnology.Bothpredictedandmeasurementresultsarepresented.

II.FILTERSTRUCTUREANDDESIGNINGEXAMPLESA.BandpassPeriodicalUnits

I.INTRODUCTION

D

UEtotheexplorationofultrawideband(UWB)tech-nologyinwirelesscommunicationsystems,UWBband-pass lters(BPFs)attractmuchresearchinterestfrombothaca-demicandcommercialindustries.Inrecentyears,numerousUWBBPFshavebeenreportedbasedonvarioustechniques[1]–[8].Themultiplemoderesonator(MMR)techniquewhichrequireshighimpedancemicrostriplinesandnarrowcouplinggapsisinitiallyproposedin[1];thecascadedhighpass/lowpass ltersandcascadedbandpassandbandstop lterswerepro-posedin[2],[3]withalargecircuitsizeandincreasedinser-tionlosses.Tosuppresstheharmonicresponseandextendtheupperstopband,theelectronic-band-gapstructuretechniqueisreportedin[4]forthedesignofUWBBPF.In[5],[6],UWBBPFsaredevelopedbyusinghybridmicrostrip/coplanar-wave-guidestructures.Toachieveacompactfootprint,severalUWBBPFshavebeendevelopedusingthemultilayerbroadside-cou-plingtechniqueandimplementedbyusingthemultilayerliquidcrystalpolymer(LCP)technology[7],[8],andUWBBPFs

ManuscriptreceivedOctober16,2009;revisedJanuary08,2010.Firstpub-lishedMarch11,2010;currentversionpublishedApril07,2010.ThisworkwassupportedbytheU.K.EngineeringandPhysicalScienceResearchCouncil(EP/E02923X/1).

TheauthorsarewiththeDepartmentofElectrical,ElectronicandComputerEngineering,SchoolofEngineeringandPhysicalSciences,Heriot-WattUni-versity,EdinburghEH144AS,U.K.(e-mail:z.c.hao@hw.ac.uk;j.hong@hw.ac.uk).

Colorversionsofoneormoreofthe guresinthisletterareavailableonlineathttp://www.77cn.com.cn.

DigitalObjectIdenti er10.1109/LMWC.2010.2042551

Fig.1showsthethree-dimensionalstructurefortheproposedperiodicalunit,whichconsistsoffourmetallayers.Thebroad-sidecoupledpatchesarelocatedatthetopandsecondlayers,respectively.Twoslotsareetchedonthegroundunderneaththebroadsidecoupledpatches,andaquarter-wavelengthres-onatorisintegratedbetweenthebroadsidecoupledpatchesandtheslottedground.TheequivalentcircuitshowninFig.2canbeusedtoexplaintheoperationprincipleoftheperiodicalunit.Thebroadsidecoupledpatchescanberepresentedbyseriescapaci-

tors,;theetchedslotcanbemodeledbyseriesparallel-res-onatorwhichisformedby

shunt

and.Theintegratedquarter-wavelengthresonatorismodeledbyshuntseries-res-and.Thecapacitorsandinduc-onatorformedby

shunt

torsoftheequivalentcircuitcanbeextractedbymatchingtheresponseoftheequivalentcircuitandthefull-wave

simulated

oftheperiodicalunit,asillustratedinFig.3.Theproposedperiodicalunitexhibitsabandpassbehavior.Itcanprovidetwotransmissionzeroswhicharegeneratedbytheetchedslotsandtheintegratedquarter-wavelengthresonator,respectively.Inourdesign,theuppercutofffrequencyisdeterminedbytheuppersidetransmissionzero,andthelowercut-offfrequencyisde-.Generally,thebiggerterminedbythebroadside

coupling

broadside-coupledpatchesandthesmallerthicknessbetweenthetopandsecondlayersresultinastrongercoupling,whichdecreasesthesmallerlowercutofffrequency.Thelowersidetransmissionzerocanbeusedtoimprovetheselectivityofthelowerpassband-edge.

Thetransmissionzeroscanbedesignedindependently.Fig.3showsthefull-wave

simulatedoftheproposedperiodicalunitwithvariedgeometries[11],wherealosslessassumptionis

1531-1309/$26.00©2010IEEE

利用多层液态晶体高分子聚合物技术(Multilayer Liquid Crystal Polymer Technology)设计的具有椭圆响应的多层超宽带(UWB)带通滤波器,

HAOANDHONG:QUASI-ELLIPTICUWBBPF

203

Fig.1.Three-dimensionalstructureforproposedperiodicalunit(allvariablesarein

millimeter).

Fig.2.Equivalentcircuitforproposedperiodical

unit.

Fig.4.3-DStructureandlayoutsforproposedUWB lter.(a)3-Dstructure;(b)toplayer;(c)secondlayer;(d)thirdlayer;(e)bottomlayer(alldim …… 此处隐藏：8948字，全部文档内容请下载后查看。喜欢就下载吧 ……