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1、ThehelicalantennaforthecapsuleendoscopeSangilKwakKihunChang,andYoungJoongYoonDepartmentofElectrical&ElectronicEng.,YonseiUniv.,Seoul,120-749,KoreaE-mail:lovekwak(konsei.ac.krAbstractInthispaper,thehelicalantennaforcapsuleendoscopeisdesigned.Toencasethesysteminasmallcapsulemodulea
2、ndtoobtainomni-directionalradiationpattemfordetectingthetransmittedsignalindependentofthetransmitterpositions,andtoobtainwidebandwidth,asmallsizednormalmodehelicalantennawhichendisconnectedtothegroundisdesigned.Thediameterandtheheightofthehelixare8mmand5.6mm,respectively.Measured
3、resultsshowthattheantennahas32MHzbandwidthforVSWR<2,andtheomni-directionalradiationpattern.IntroductionMostoftheresearchonmicrowaveantennasformedicalapplicationshasfocusedonhyperthermiaorcapsuleendoscope[1].Thecapsuleendoscopesystemwhichiscomposedofsensorsandtheirassociatedcircui
4、tryandtransmitterisencasedin"capsule"thatissmallenoughtobeswallowedandtraversedtheentiredigestivetractwhiletransmittingtheirreadingstoanextemalreceiver[2].Thecapsuleendoscopesystemwasintroducedjustfewyearsago,thusincontrasttoanumberofresearchesofaccomplishmentsrelatedtohypertherm
5、ia,studiesoncapsuleendoscopeforbiotelemetryarenotwidelyreported[3].Toencasethesystemincapsulemodule,averysmallsizedtransmitterisrequired.Also,sincethecapsulemoduleislocatedinsidethehumanbody,thehumanbodytissueshaveeffectsontheantennapropagationcharacteristicsisconsidered[4],[5].A
6、ndtodetectthetransmittedsignalindependentoftransmitterpositions,theantennaisrequiredomni-directionalradiationpattern.Inthispaper,thehelicalantennaforcapsuleendoscopeisdesigned.AntennaDesignTheconfigurationofthedesignedhelicalantennaisshowninFig.1.Toencasetheantennaincapsulemodule
7、,averysmallsizedNMH-IA(Normalmodehelicalantenna)isdesigned.Thedesignedantennahas7tum-loopswith0.5mmwidthconductor.Thediameterofthehelixis8mmandtheantennaheightis5.6mm.0-7803-8883-6/05/$20.00@2005IEEE804Thetransmitterofthecapsuleendoscoperequiressufficientbandwidthtotransmitthehum
8、anbodyinformation,likeacolonandastomachr