레이더 기술 소개 - huniv.hongik.ac.kr

1 , 2009 5 11 , 1 (Introduction to the Radar Technology) 2009. 5. 11.( ). (13:00-15:00) . , 2009 5 11 , 21. ( ) --------------------- 3-. -. 2. ---------------------------- 19-. , RCS-. , , 3. ---------------------------- 29-. -. (Interference, )4. ---------------------------------- 35-. -. 5. / ---------------------------- 49-. Canceller-. SAR speckle6. ---------------------------------- 53 , 2009 5 11 , 31. ( ) Radar (Radio detection and ranging) Microwave Active Sensor Sensors.

2 Passive sensors: Human eyes ( ), Camera, Radiometer (Microwave, Infrared(IR)) Measure Brightness Temperature-. Active sensors:Radar ( ), Measure RCS(radar cross section)Lidar (IR)Radar:-. Transmitter ( , Camera )-. Microwave (IR , ) ??? ???1941 Radar , . , 2009 5 11 , 4 : Point target ( , ):-. Range -. Angle (Direction)-. Speed ( speed gun), < GPS > FM-CW, pulse -Doppler radars Electronic mechanical Scanning : 2D 3D Search (surveillance) radar : Servo-motor trackingDistributed Targets.

3 Weather, -. Altitude-. Terrain (Remote Sensing Earth)-. Scatterometers -. Synthetic Aperture Radar (SAR) Images2 . , 2009 5 11 , 5 Point Target CW (continuous wave) Radar ftft+fDvR DDfvvRvvRvf = = = cos2 2 2 fd>0, fd<0, 90 fd=0fD: Doppler FrequencyR: rangev: velocityft+ and ProcessingfDftftAntennaSwitch < ooo Speed Gun > Speed detection , 2009 5 11 , 6 pulse RadarPulse-Doppler Radar Range detection + Speed detection : Pozar, Microwave Engineering, 1998 cRTd2=Time delay: R: rangec: wave speed , 2009 5 11 , fbf1f2fd7FM-CW RadarRange DetectionSpeed Detection.

4 Ulaby et al, Microwave Remote Sensing, 1986 RcTBcRTBfcRTandTBTfRRRRR422)ffrequencybe at (22b=== == B: modulation bandwidth (Hz)TR: modulation period )(21221speedvfffffffffddbdb = =+= , 2009 5 11 , 8 Chirp ( pulse compression ) RadarPulse Radar:tPptPt: Peak transmit power device tp: pulse range resolution tPptChirp Radar:Chirp Radar: FM + pulse Peak Power Chirped pulsetPptDe-chirped output2f1fttptESAW: surface acoustic waveSAW Filter<Transmit> <Receive>fIF=2-1 GHz, fLO=8 GHz fRF=10-9 GHzfRF=10-9 GHz, fLO=11 GHz fIF=1-2 GHzFor example:SAW FilterFMChirp , 2009 5 11 , 9 : Ulaby et al, Microwave Remote Sensing, 1986 Binary-phase-code Chirp Radar+1-1 3=t-1+1-1 = -1 7=t+1+1+1+1+1+1+1 = 7M087706150413021 = = = = = = = = tttttttt , 2009 5 11 , 10 Distributed Target Altimeter : measure heightScatterometer: measure scattering coefficient Imaging radar.

5 Side-looking airborne radar (SLAR)(real aperture radar)-. Synthetic aperture radar (SAR)-. KOMPSAT-5 ( 5 ; ; 2010)-. Cosmo SkyMed ( ; 2008; X- )-. RADARSAT-2 ( ; 2007; C- )-. TerraSAR-X ( ; 2007; X- )-. PALSAR ( ; 2006; L- )-. ENVISAT ASAR ( ; 2002; C- )Space Shuttle Endeavour ( , ) (Challenger 2010 ) , 2009 5 11 , 11 (KOMPSAT-5)DataReceiverScattering from Earth SurfacesApplication( ) Microwave ScatteringEarth Remote Sensing ( , ) < CO2> ( , / , ) ( , , ) , 2009 5 11 , 12 A region of south-central Egypt Radar Interferometry ( ) Microwave.

6 Transmission through atmosphere-. Penetrate clouds (to some extent rain).-. Penetrate into vegetation (and into ground).-. In addition to their independence of the sun , 2009 5 11 , 13A visual show of the electromagnetic wave scattering : , 2009 5 11 , 14 (Hardware)PowerDividerLocalOscillatorDup lex,CirculatorDown-ConverterPower and Power Supply(to all)Signal and Data ProcessingDisplayand RecordUp-ConverterBand-PassFilterLow-Pas sFilter , 2009 5 11 , 152468101214161820-70-60-50-40-30-20-100 Frequency [GHz].output power [dBm]Receiver Harmonic Signal Generator 0dBm 1~ Spectrum AnalyzerUp-ConverterDown-ConverterMixer LO ( GHz)RF ( GHz)ImagesIF ( GHz)HarmonicsNoise Level , 2009 5 11 , 16 Aperture antennas: Aperture field Field SourceLinear antennas: Current Field Source Dipole TargetInduced current 2 , 2009 5 11 , 17 A/D converter Digital Signal Processing RCS (calibration) Range Ambiguity.

7 PpfT1=Target-1 Target-2pulse-1T1 T2T1 T2pulse-2 Ambiguous (not distinguished)sRcRTsR2=Ambiguity :spspRpRcfcRfTT221< > > jittered pulse interval 1pT2pT3pT PRF( pulse repetition frequency) fp: pulse repetition frequency , 2009 5 11 , 18 Speed (Doppler) AmbiguityTp: pulse periodTd1 TpTd2Td: Doppler wave periodddfT1=AmbiguousDetects u1instead of 3u1 PRF Nyquist rate .)2(2dpdpTTff , Range ambiguity PRF ,Doppler (speed) ambiguity PRF .max,max,22spdRcff : PRF ( Trade-off) , 2009 5 11 , 192. X (Spatial Displacement)Wave HeightT (Time)Wave HeightWater Wave:Snap shot:Float movement:()xkztEtzE cos),(0 = Magnitude(source,distance,etc.)

8 SinusoidalWaveTimeVariationZ-directedpro pagationVector(Polarization)T = 2 =2kTimeTxEz, distance xEEM Wave: ( ; Radiowave Propagation) , 2009 5 11 , 2020 gain antennatransmit:power er transmittaverage:ttGP24)(RGPRItt =Power density at the target:ttGP EIRP:Effective isotropic radiated power RCS (radar cross section): )(RIPsc Spherical surface area:24R RPsc=scattered power in a direction )(RIPsc=recI )(RIPoint targets: , 2009 5 11 , 21 Received signal Power (W) at receiver: PserecsAIP=where Aeis the effective aperture area: 42 DAe=()()()WRGGPRAGPP rttetts 4322244==: Radar equation (bistatic)Power density (W/m2) at receiver.

9 Irec()222244)(4 RGPRRIRPI ttscrec === ( )Radar equation (mono-static) ()()WRGPPts 43224= , 2009 5 11 , 22()()dsRgAareaillumill =.42,, Distributed targets:() ( )()()illtSttSrAGPdsRgGPdsRgGPP0322042032 2004322204),(),(4),(4),( = = = , illumination integral: AntennaIlluminated area(foot print)R0 : (scattering coefficient) dB : RCS (point target) m2, dBsm (dBm2) , 2009 5 11 , 23 Microwave Ionospherereflection : Curlander & McDonoughSynthetic Aperture Radar,Systems and Signal Processing, Wiley Series, vapor: 22 GHzOxygen: 60, 120 GHzL-band: 1 - 2 GHzC-band: 4 - 8 GHzX-band.

10 8 - 12 GHzAbsorption , 2009 5 11 , leg length, a (m)RCS (dBsm)X-band ( )C-band ( )L-band ( ) Corner Reflector RCS Conducting sphere RCS ( )2224)(3434 aaa==( )Optical : 2a = : Pozar, Microwave Engineering, 1998 , 2009 5 11 , 25 (polarization): shape of the locus of the E vector tipat a given point in space as a function of time. ()()jkzjyxeeyaxazE += = ,0 PolarizationLinearCircularElliptical2, = =yxaaOther CasesConditionsExamplesxeEzEjkz )(0 =()()jkzeyjxzE = ()()jkzeyjxzE = 2 Perpendicular PolarizationParallelPolarizationiEiHxz iEiHxz , 2009 5 11 , 26 (polarization) ( )Polarimetric Scatterometer :( )TxRxSW-1SW-2 CirculatorCirculatorTransmitterReceiverV VHHSW-1SW-2V - V H -V V -H H-HOMTHornAntennaEHPS (Hongik PolarimetricScatterometer) , 2009 5 11 , 27 (polarization) ( )Power Line ( ).