搜索
RFQuiz#11.Whatistheimpedanceoffreespace?377ou2.Whathappenstothenoisefigureofareceiverwhena10dBattenuatorisaddedattheinput?a)Noisefigureincreasesby10dBb)Noisefiguredecreasesby10dBc)Noisefiguredoesn'tchange3.AnRFsystemhasalinearthroughputgainof+10dBandanoutput3rd-orderinterceptpoint(OIP3)of+30dBm.Whatistheinput3rd-orderinterceptpoint(IIP3)?a)+20dBmb)+40dBmc)+30dBm4.Whichfiltertypehasthegreatestselectivityforagivenorder(i.e.,N=5)?a)Besselb)Chebychev(ripple=0.1dB)c)Butterworth5.Whichmixerspuriousproductisa5th-orderproduct?a)1*LO+5*RFb)6*LO-1*RFc)3*LO-2*IF6.A2.8GHzoscillatorisphase-lockedtoa10MHzreferenceoscillatorthathasasingle-sidedphasenoiseof-100dBcat1kHzoffset.Whatisthesingle-sidedphasenoiseofthe2.8GHzoscillatorat1kHzoffset?a)-48.6dBcb)-100dBcc)-51.1dBc7.Whatisthepowerofa2Vpk-pksinewaveacrossa50ohmload?a)-20.0dBmb)+10.0dBmc)+19.0dBm8.Which2-portS-parameteriscommonlyreferredtoasreverseisolationinanamplifier?a)S21b)S22c)S129.WhataretheminimumandmaximumcombinedVSWRlimitsataninterfacecharacterizedbya1.25:1VSWRanda2.00:1VSWR?a)1.75:1(min),2.25:1(max)b)1.60:1(min),2.50:1(max)c)0.75:1(min),3.25:1(max)10.Anidealdirectionalcouplerhasadirectivityof25dBandanisolationof40dB.Whatisitscouplingvalue?I=D+Ca)65dBb)40dBc)15dBRFQuiz#21.OnaSmithchart,whatdoesapointinthebottomhalfofthechartrepresent?a)Aninductiveimpedanceb)Acapacitiveimpedancec)Powersaturation2.Whilewe'reonthesubjectofSmithcharts,whatistheimpedanceofthepointatthefarleftedgeofthecenterhorizontalline?a)Infiniteohms(opencircuit)b)Zeroohms(shortcircuit)c)50ohmmatch3.Asingle-conversiondownconverterusesahigh-sidelocaloscillator(LO)totranslatetheinputradiofrequency(RF)toanintermediatefrequency(IF).WillspectralinversionoccuratIF?a)Yes,alwaysb)No,neverc)Sometimes4.Whathappenstothenoisefloorofaspectrumanalyzerwhentheinputfilterresolutionbandwidthisdecreasedbytwodecades?a)20dBincreaseb)20dBdecreasec)40dBdecrease5.Whatisaprimaryadvantageofaquadraturemodulator?a)LowLOpowerrequiredb)Fourseparateoutputsc)Single-sidebandoutput6.WhatismeantbydBiasappliedtoantennas?a)Isolationindecibelsb)Physicalsizerelativetointrinsicantennasc)Gainrelativetoanisotropicradiator7.Whatisthepowerdynamicrangeofanideal12-bitanalog-to-digitalconverter(ADC)?a)36.12dBb)120dBc)72.25dB8.Anideal10dBattenuatorisaddedinfrontofaloadthathasa2.00:1VSWR.WhatistheresultingVSWRoftheload+attenuator?a)1.07:1b)2.10:1c)12.0:19.Whatisthethermalnoisepowerina1MHzbandwidthwhenthesystemtemperatureis15degreesCelsius(assumegainandnoisefigureare0dB)?a)-114.0dBm(ina1MHzbandwidth)b)-114.0dBmc)-114.0dBm/Hz10.Twoequalamplitudetoneshaveapowerof+10dBm,andgenerateapairofequalamplitude3rd-orderintermodulationproductsat-20dBm.Whatisthe2-tone,3rd-orderinterceptpoint(IP3)ofthesystem?a)+40dBmb)+25dBmc)+20dBmRFQuiz#31.Whatisaprimaryadvantagetousing90degree(quadrature)hybridcouplersinamplifierdesigns?a)Widerbandwidthpossibleb)Lownoisefigurec)Input/outputimpedancenotdependentondevicesaslongasdeviceimpedancesareequal2.Whyisthereafrequencytermintheequationforfree-spacepathloss?a)Thereisnofrequencytermb)Atmosphericabsorptionc)Antennageometryrequiresit3.Ifanamplifierhasanoisetemperatureof60K,whatisitsnoisefigureforanambienttemperatureof290K?a)8.0dBb)80dBc)0.82dB4.Whatisaprimaryadvantageofoffset-quadrature-phase-shift-keying(OQPSK)overstandardQPSK?a)Greaterdataratespossibleb)Greaterspectralefficiencyc)Moreconstantenvelopepower5.Amixerhasthefollowinginputfrequencies:RF=800MHz,LO=870MHz.Thedesiredoutputfrequencyis70MHz.Whatistheimagefrequency?a)940MHzb)1670MHzc)140MHz6.Whatisthespurious-freedynamicrangeofasystemwithIP3=+30dBmandaminimumdiscerniblesignal(MDS)levelof-90dBm?a)80dBb)120dBc)60dB7.Aspectrumanalyzerdisplaysacomponentat10MHz@0dBm,30MHz@-10dBm,50MHz@-14dBm,70MHz@-17dBm,andalloftheotheroddharmonicsuntiltheydisappearintothenoise.Whatwasthemostlikelyinputsignalthatcausedthespectrum?a)A10MHzsquarewave(0Vdc)b)A10MHztrianglewave(0Vdc)c)A10MHzcosinewave(0Vdc)8.OnwhichsideofarectangularwaveguideisanE-bendmade?a)Thelongdimensionb)Theshortdimensionc)Theinside9.Duringanetworkanalyzercalibration,whyarebothashortcircuitandanopencircuitused?a)Theyaverageto50ohmsinanRFsystemb)Todeterminethecharacteristicimpedanceofthemeasurementsystemc)Bothareeasytoproducetoathighaccuracy10.Whatisthefirstharmonicof1GHz?a)1GHzb)2GHzc)10GHzRFQuiz#41.Whichofthefollowingcancausefrequencyintermodulationproductsinasystem?a)Onlysemiconductorjunctionslikediodesandtransistors(amplifiers)b)Cableconnectors,boltedorrivetedantennapanels,isolatorsandcirculatorsc)Botha)andb)2.Whatisthemeltingtemperatureofstandard60/40,tin/leadsolder?a)100°C(212°F)b)250°C(482°F)c)186°C(386°F)3.Whatisthefrequencybandforthe900MHzGSMcellularband?a)Tx:880-915MHz/Rx:925-960MHzb)Tx:824-849MHz/Rx:869-894MHzc)Thereisno900MHzGSMband4.WhatdoesGSMstandfor?a)GeneralSystemforMobilephonesb)GreaterSpectrumforMobilephonesc)GlobalSystemforMobileCommunication5.WhatdoesPOTSstandfor(incommunications)?a)PlainOldTelephoneSystemb)PersOnalTelephonySystemc)PersonalOrbital&TerrestrialSatellite6.Whichofthesepairsofmaterialsinthet