Design and Analysis of Leakywave Antennas for Novel Functionalities

Abstract

This thesisdealswiththeeffectivedesignofplanarleakywaveantennas(LWA)for novelfunctionalities.Theworkdescribesamethodologybasedonsingle-layertrans- mission basedGoubaulineandinvestigationofasymmetryinHalf-modesubstratein- tegratedwaveguide(HMSIW)periodicLWAstoaddressverydifferentantennaconfig- urations. FournovelLWAsareproposedtoachievewideanglebeamscanning,single layer basedEnd-Fireradiation,dual-bandandsimultaneousdual-beamscanningfunc- tionalities. WidebeamscanningisdesignedusingGoubauline.Incontrasttotheconventional LWAwithasmallscanninganglerangeandlowefficiency,thisworkemployedape- riodically bendingGoubauline,whichnotonlybringsinaperiodicperturbationfor leakywaveradiation,butalsoenhancesthescanningrangeduetotheincreaseddelay for eachlineelement.Theproposedantennafeaturesgoodradiationperformanceand has acompactandlowprofileconfiguration.Also,asimpleandlow-profilePlanar Goubau linebasedEndfireantennaisdesigned.Endfireradiationisachievedbymod- ifying theGoubaulineintoinvertedperiodicarrangementofV-shapedunitcells.The proposed endfireantennahasasinglemetalliclayerwithasimpleconfigurationwhich is easytofabricateandalsoeasytointegratewithotherelectronicscircuits. Most oftheexistingLWAsaregenerallydesignedforasinglebandapplication.In this work,byetchingsimplespiraltypeslotsontheHMSIWcavity,anoveldual-band dual-polarized LWAisdesigned.Theantennaradiatesthelinearlypolarized(LP)wave in thelowerbandandcircularlypolarizedwaveinthehigheroperatingband.Inthe higher operatingbandantennaexhibitsbothright-handcircularpolarization(RHCP) as wellasthelefthand(LHCP)circularpolarizationinthenearmainbeamdirection. Also, asymmetryisinvestigatedinHMSIWLWA.Basedonasymmetry,twodifferent configurations ofdual-bandLWAsaredesigned.ThefirstconfigurationradiatesLP v wavesinthelowerbandandCPwavesintheupperbandwhentheunitcellsarecas- caded sequentially.Thesecondconfiguration,wherethesidewallviaoftheHMSIW unit cellsareconnectedalternatingly,providessimultaneousdual-beamswithdiffer- ent polarizationintheupperoperationalbandinadditiontotheLPbeaminthelower operational band.ThesenovelfunctionalitiesofLWAcanbeeffectivelyusedformulti- objectivetrackingapplicationsandforenhancingthechannelcapacityofautomotive and satellite-basedwirelesscommunicationsystems.Sincebothantennaconfigurations had dualfrequencybandswithdifferentpointingdirectionsinscanning,itcanalsobe useful forvehicularapplicationstotrackdifferentobjectsinitsnearbylocations Proposed designsarefabricatedusingLPKFprotomatmachineS103andexperi- mentally verifiedusingradiationpatternmeasurementset-up.Impedancebandwidth, peak gain,axialratiobandwidthandradiationefficiencyaremeasuredandcompared with thesimulatedresults.Theperformanceoftheproposedworksarecomparedwith the previousliterature.