Themeasurement,monitoringofheartbeatanditsratearenecessarytoknowthehealthoftheheartofhumanbeings.Inaddition,theyareneededforapplicationslikecriminalinvestigation,lawenforcement,defenseandmilitaryusage,search,rescueoperationetc.Theultra-wideband(UWB)radarsfoundgrowinginterestinrecentyearsastheyareabletoovercomethelimitationsofcontinuous-wave(CW)Dopplerradarsindetectinghumanheartbeat.ModellingandanalysisoftheUWBpulsepropagationbehaviorthroughahumanbodyisimportanttoinitiatethebuildingofapracticalUWBradar.Severalresearchershaveestimatedthereflectedsignalstostudyiftheirvariationscorrelatewiththeheartbeatrate.However,thereflectedsignalstrengthcarryingDopplerinformationreceivedattheradarafteratwo-waypropagationoftheRFsignalwasfoundtobetooweakfordetection.Studyofmonitoringcardiacactivityusingradarprincipleshasbecomeapromisingmeansforvariousdetectionand/ormonitoringhealthissues.Therearemanymajorbiomedicalapplications,modernpotentialmethodsofcriminalinvestigationswhicharebasedontheheartbeatperformanceofthehumansubject.Insuchcases,detectionofthesmallamplitudeofheartbeatbecomesimperative.Thecontactbasedmethodssuchasstethoscopeorelectrocardiogram(ECG),requirephysicalcontactwiththehumanbodyandwasfoundtobeineffectiveincriminalinvestigations.1Heartbeatmeasurementcanbemoreeffective,ifthemethodofdetectionofheartbeatissuchthatthehumansubjectisunawareofbeingundertest.Moreover,thecontactbasedmethodshavetheconstraintthattheydependontheaccessibilityoftheaffectedpartofthesubject.ECGelectrodesneedpreparationpriortothemeasurementandcancauseirritationforinfantsorburnvictims.Moreover,themedicalpersonnelmightneedmoretimeforthepreparationofsensorsthatprovidesignalsforthethoraxareamedicalimaging.Sodetectionand/ormonitoringofcardiacperformanceusingnon-contactbasedmethodslikeradarsbecomepromisingastheyarenon-invasiveandsuitableincaseofinaccessiblehumansubjectsaswell,byplacingtheradarataremotelocation,awayfromthesubjectunderobservation.AlthoughtheCWDopplerradarsarestillbeingappreciatedandrefinedforassessmentofhumanlife-signs,therecentyearshavespawnedgrowinginterestintheuseofUWBradarsformedicalapplicationsduetoitsmultipleadvantageousfeatures.2-4FollowingtheinventionofthefirstUWBradarmodelbyMcEwanandtwoofhispatentsin1996and1998,respectively,therehavebeencontinuouseffortstodeterminethefeasibilityofaUWBradartodetectcardiacactivities.5-7VariousUWBradarmodelsforheartbeatdetectionwithdirectexposureofUWBsignaltothehumanbeinghavebeenreportedbyseveralresearchers.8-19ThestudyofheartbeatdetectionwithrealtimemeasurementsusingUWBradarhasbeenfoundintheliterature.20-23Inthispaper,thetransmissioncoefficientsareestimatedfromaplanarmultilayeredstructureofthehumanthoraxusingCSTMicrowaveStudio(MWS).ThecalculationsofthetransmissioncoefficientsoftheUWBsignalhavebeenperformedconsideringthefrequencydependentpropertiesofvariouslayersandthemultiplereflectionsthattakeplaceattheboundaries.Ithasbeenobservedthatthebasiccharacteristicoftheheart,namely,theheartbeatrateessentiallydependsonthevariationofheartdimensions.StudieshaveshownthatthetimedependenttransmissioncharacteristicsatspecificfrequenciesofUWBdoindicatetheheartbeatrate,thusleadingtothepossibilityofusingthetransmissioncoefficientasaparametertoestimatethestrengthoftheheart.