Development of SAR-based UWB See-Through-Wall Radar
Yunqiang Yang Song Lin
Alex Zhang
Department of Electrical and Computer Engineering
University of Tennessee, Knoxville
Outline
Background Information Electromagnetic/Antenna Aspects UWB Components Design/DAQ Aspects Imaging Processing Aspects See-Thru-Wall Experiment Future Work
See-Thru-Wall Goals
Search Operation
Tactical Operation
provide dismounted and remote users with the capability to detect, locate and “see” personnel with concealed weapons/explosives behind obstructions from a standoff distance
Increased force protection and survivability of soldier in during operations, combat search and rescue, and hostage recovery operations.
Provide initial information on building layout and enemy personnel locations
Why Microwave UWB Radar?
Optical Quality Images at Microwave Frequencies Active System – Day and Night Imaging Adverse Weather Long Stand-off Ability (fine resolution imaging independent
of range) Both Broad and Spot Coverage Coherent Imaging Bi-static and Multi-static Configurations (transmitter
separate from receiver provides stealth) Penetration of Materials and Particulates (frequency
dependent) Detection of Ground Moving Target
Microwave Imaging
AdvantagesDay/night, all weatherPenetration (e.g. buildings)
Good scene recognition Poor object recognition
DisadvantagesNon-literal imagery
Imaging Fundamentals
Optical ImagesAngle vs. Angle
Microwave ImagesRange vs. Angle
CrossrangeAngle
RangeAngle
Optical Quality at Radar Frequency
Interior Image of Mannequin
Mannequin Only Mannequin Behind WallPhotograph
Resolution vs. Frequency
What controls the resolution of these
systems?
Downrange resolution is solely based on bandwidth in conventional RADAR (i.e. CW, FMCW)
UWB range resolution is based on the pulse width
meanwhile cross range timing resolution in a single antenna setup is a function of the antenna beamwidth (θ), where R is range
Multiple element or SAR system cross range resolution is a function of their effective aperture (L) and wavelength (λ)
B
cR
2
RAr
L
RAr
See-Through Wall Radar Prototype
RF Transceiver DAC/Control
Image Processing
Wall
Radar Rage: 20 m Radar PRF: 5 MHzPulse Width: 0.5 ns Center Frequency: 10 GHzHand-held portable/Ground Vehicle-Based System
Wave-propagation through the wall, and characterization of various Walls: Dielectric Constant, conductivity, attenuation Loss
Efficient EM modeling of scattering from objects inside a room
Wall parameter effects
Role of polarization in image enhancement Low-profile printed antennas/arrays for the system
Electromagnetic/Antenna Aspects of the System
UWB components design: power amplifier, low noise amplifier, power divider, SP16T switch, mixer, pulse generator.
Sampling of UWB signal: equivalent time sampling technique
UWB Transceiver Design and Data Acquisition Aspects
Image Processing Issues
Improve two-dimensional imaging resolution
Reduce antenna size
Mitigate the effects of the wall
Imaging quality depends on: Bandwidth, Baseline range, Wall distortions,
Wall uniformity, Wall absorption, Positioning errors
RF Attenuation in Different Wall Materials
N.C. Currie, D.D. Ferris, and al, “New law enforcement application of millimeter wave radar”, SPIE Vol. 3066, pp2-10, 1997
Propagation Modeling
Frequency domain measurement VNA for insertion transfer function.
Advanced Design System (ADS) models
UWB Antenna Consideration
Wide band-width Good impedance match Minimum waveform ringing Minimum pulse dispersion Small size Low cost
Types of UWB Antennas
Tapered slot: Two dimensional microstrip TEM horn: Most commonly used Bow-tie: Relatively high input impedance Requires a matching balun Resister loaded dipole Low gain and low efficiency Discone: High performance, Difficult to manufacture 3-D structure Bicone: High performance, Difficult to manufacture 3-D structure Log-periodic: Dispersive Spiral: Dispersive
Antipodal Vivaldi Antenna
Tapered flares on different layersDimension: 2.15cm x 5.52cm
Substrate: Roger 4003C, 10 mil-thick
Developed by Gibson in 1979 Wide band performance Fabricated on dielectric substrates Great potential to low cost and weight Small size
Vivaldi Sub-array
16 Element sub-array Dim: 18 cm x 40 cm Wilkinson power divider Element spacing: 2.15 cm
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
4 6 8 10 12 14 16f (GHz)
S11
(dB
)
7.5 GHz – 12.5 GHz
Pattern: Simulation Versus Measurement
@ 10 GHz
Measurement: 13dB Gain, 4° BeamwidthSimulation: 15dB Gain, 3° Beamwidth
Measured Radiation Pattern
E Plane
H Plane
Transmitter/Receiver Structure
Switch
1 2 3 4 16
........
System Block Diagram
UWB See-Through-Wall Imaging RadarSimulation (in ADS)
UWB See-Through-Wall Imaging Radar
VAR
VAR5
PulseEnergy_joule=.535e-10
Tstep=10 psec
EqnVar
VAR
VAR7Tmax=100 psec
EqnVar
VARglobal VAR6
LO_Freq=10 GHzPower_LO=-13 _dBm
EqnVar
VARVAR4
Tstop=(0.1*n) us
n=2PulseWidth=1 nsec
EqnVar
Tran
Tran1
ImpMaxPts=40960ImpMaxFreq=10 GHz
TimeStepControl=FixedMinTimeStep=Tstep
MaxTimeStep=TmaxStopTime=0.2 usec
StartTime=0 psec
TRANSIENT
DFDF
OutVar=DefaultTimeStop=Tstop
DefaultTimeStart=0 secDefaultNumericStop=Tstop/Tstep
DefaultNumericStart=0
uwb_antennaX4
freq=8-12 GHz
R X _ O U T
T X _ I N
RXTX
Rx_rX9
LOinput Rxintput
Ioutput
Qou
tput
2
43
1
Tx_rX8
Pulseinput
LOo
utput
Calibra
tion
Txoutput2
43
1
RES
R1R=50 Ohm
SpectrumAnalyzerFilter_Input_Spectrum3
RESR2R=50 Ohm
SpectrumAnalyzerFilter_Input_Spectrum2
TimedSinkFilterInput_Time1
Stop=0.2 usecStart=0 sec
SpectrumAnalyzer
Filter_Input_Spectrum1
TimedSinkFilterInput_Time2
TimedSinkFilterInput_Time3
RESR3R=50 Ohm
ImpulseFloatI1
Delay=100
Period=Tstop/(n*Tstep)Level=1.0
PULSE_SHAPE_GENERATORX1
TStep=TstepDoubletSeparation=350 psec
PulseEnergy_joule=PulseEnergy_joulePulseWidth=PulseWidth
Pulse ShapeGenerator
PulseO utputTriggerI nput
SpectrumAnalyzerFilter_Input_Spectrum
FloatToTimedF1
TStep=Tstep
TimedSink
FilterInput_Time
UWB_SubHarmonic_Mixer
Why SubHarmonic_Mixer? 1. Easy to implement in a PCB technology using coplanar
lines. 2. LO frequency can be lowered 3. Provides very high isolation between the RF port , LO
port and IF port. Specially the RF and LO have more than 40 dB isolation in the 8-12 GHz frequency range.
UWB_SubHarmonic_Mixer Simulation
IFIF
RF
RF
LOLO
MCLINCLin1
L=122 milS=6 milW=34 milSubst="MSub1"
MLOCTL1
L=LSW=WSSubst="MSub1"
TermTerm2
Z=50Num=2
MLINTL38
L=l21W=w
MTEETee2
W3=10 milW2=wW1=w
MLINTL32
L=l24W=w
MRSTUBStub2
Angle=60L=RFstub1Wi=10 milSubst="MSub1"
MLINTL40
L=100.0 milW=45.0 milSubst="MSub1"
MCORNCorn1
W=WSTEPSubst="MSub1"
MLOCTL2
L=1 milW=34 milSubst="MSub1"
bfp_layout_1bfp_layout_1_1ModelType=MW
Ref
mrstub7ghz2newmrstub7ghz2new_1ModelType=MW
Ref
MRSTUBStub1
Angle=60L=LOstubWi=10.0 milSubst="MSub1"
MTEETee4
W3=10 milW2=wW1=w31
MSUBMSub1
Rough=0 milTanD=0.0027T=0.1 milHu=3.9e+034 milCond=5.88E+7Mur=1Er=3.38H=20 mil
MSub
HarmonicBalanceHB2
Order[3]=3Order[2]=3Order[1]=5Freq[3]=IFfreq2Freq[2]=IFfreq1Freq[1]=LOfreq
HARMONIC BALANCE
LOBFPLOBFP_1ModelType=MW
RefP_nHarmPORT3
P[1]=polar(dbmtow(P_LO),0)Freq=LOfreqZ=50 OhmNum=3
MLINTL35
L=100 milW=w
MLINTL33
L=l32W=w32
VIAV1
W=10.0 milT=0.125 milH=20 milD2=15 milD1=20 mil
MTEETee1
W3=w32W2=w31W1=ww
MTEETee7
W3=wW2=wW1=w
MTEETee6
W3=10 milW2=wwW1=w
P_nTonePORT4
P[2]=polar(dbmtow(P_IF),0)P[1]=polar(dbmtow(P_IF),0)Freq[2]=IFfreq2Freq[1]=IFfreq1Z=50 OhmNum=4
MLINTL37
L=50 milW=w
MRSTUBStub4
Angle=60L=IFstubWi=10 milSubst="MSub1"
MLINTL23
L=lIFW=w
MTEETee5
W3=10 milW2=wW1=w
MRSTUBStub3
Angle=60L=matchWi=10.0 milSubst="MSub1"
MLINTL39
L=l22W=w
MLINTL24
L=l11W=ww
di_hp_HSMS8202_20000301D10
MLINTL31
L=l31W=w31
MLINTL30
L=l33W=ww
Harmonic Mixer
Frequency Range, RF: 8 - 12GHz
Frequency Range, LO: 8 - 12GHz
Frequency Range, IF: 0.1- 2.5GHz
Conversion loss <13dB
RF to LO isolation > 45dB
RF to IF isolation > 45dB
LO to IF isolation > 45dB
IP3 (Input) 14dBm
LO input power : 7dBm
Parallel-Feedback Dielectric-Resonator Oscillator
Why DRO? DROs are attractive microwave sources because
of their high Q, low phase noise, good output power and their high stability versus temperature.
They represent a good compromise of costs, size, and performance compared to alternative signal sources such as cavity oscillators, microstrip oscillators or multiplied crystal oscillators.
The parallel-feedback with BJT DRO can achieve the highest performance in some frequency range.
DRO Simulation
vout
RR7R=41 kOhm noopt{ 10 kOhm to 45 kOhm }
MLINTL19
L=20 milW=10 milSubst="MSub1"
MRSTUBStub1
Angle=70L=lstubWi=8 milSubst="MSub1"
MTEETee6
W3=10 milW2=10 milW1=10 milSubst="MSub1"
MRSTUBStub2
Angle=70L=lstubWi=8 milSubst="MSub1"
RR2R=50 Ohm noopt{ 120 Ohm to 350 Ohm }
V_DCSRC1Vdc=5 V
CC2C=1.0 pF
MLINTL7
L=20 milW=10 milSubst="MSub1"
MLINTL18
L=lbasebW=10 milSubst="MSub1"
MTEETee5
W3=10 milW2=10 milW1=10 milSubst="MSub1"
MLINTL17
L=lbasecW=10 milSubst="MSub1"
OscPortOsc1
MaxLoopGainStep=FundIndex=1Steps=10NumOctaves=2Z=1.1 OhmV=
MLINTL12
Mod=KirschningL=l9W=30 milSubst="MSub1"
MTEETee2
W3=wbiasW2=w1W1=w1Subst="MSub1"
MCURVECurve1
Radius=80 milAngle=90W=w1Subst="MSub1"
MSUBMSub1
Rough=0 milTanD=0.0001T=0.125 milHu=3.9e+10 milCond=1.0E+40Mur=1Er=3.38H=20 mil
MSubHarmonicBalanceHB3
OscPortName="Osc1"OscMode=yesSortNoise=Sort by valueNoiseNode[1]="vout"FM_Noise=yesPhaseNoise=yesNLNoiseDec=5NLNoiseStop=50 MHzNLNoiseStart=1k HzOversample[1]=5StatusLevel=3Order[1]=7Freq[1]=10 GHz
HARMONIC BALANCE
MLINTL14
Mod=KirschningL=l6W=w1Subst="MSub1"
MLINTL13
Mod=KirschningL=l8W=w1Subst="MSub1"
MCURVECurve2
Radius=80 milAngle=90W=w1Subst="MSub1"
RR6R=500000 Ohm
TFTF2T=-0.707
TFTF1T=0.707
PRLCPRLC1
C=3.18 nFL=0.08 pHR=35 Ohm
MICAP1C3
Wf=46.0 milWt=0.05 milNp=1L=205 milGe=8 milG=6 milW=8 milSubst="MSub1"
MLINTL8
Mod=KirschningL=95 milW=w1Subst="MSub1"
MLINTL16
Mod=KirschningL=l7W=30 milSubst="MSub1"
RR4R=1000000 Ohm
MLOCTL2
Mod=KirschningL=l1W=w1Subst="MSub1"
MLINTL4
Mod=KirschningL=l3W=w1Subst="MSub1"
MLINTL6
Mod=KirschningL=l5W=w1Subst="MSub1"
MTEETee4
W3=wbiasW2=w1W1=w1Subst="MSub1"R
R5R=5000000 Ohm
BFP640_MODELB1
MLINTL3
Mod=KirschningL=l2W=w1Subst="MSub1"
MLINTL5
Mod=KirschningL=l4W=w1Subst="MSub1"
MTEETee1
W3=w1W2=w1W1=w1Subst="MSub1"
MLOCTL1
Mod=KirschningL=l1W=w1Subst="MSub1"
RR3R=50 Ohm
DRO Oscillator
Operating Frequency Range:
9.9-10.1GHz
Phase noise:
-95dBc @ 10KHz
-120dBc @ 1 MHz
Output power: 7 dBm
Harmonics: -40 dBc min
Spurious: - 80 dBc min
Temperature stability: +/- 1MHz
Narrow Band Low Noise Amplifier
Freq range: 9.9-10.1 GHz
Gain: >11.5 dB
Gain Flatness: +/- 0.5 dB
Noise figure: 1.2 dB
P1dB: 16 dBm
IP3out: 24 dBm
UWB Power Amplifier
Freq range: 2-18 GHz
Gain: >12 dB
Gain Flatness: +/- 0.5 dB
Psat: 26 dBm
P1dB: 25 dBm
IP3out: 27 dBm
UWB System TopologyUWB System Topology
SP16T With Antenna ArraySP16T With Antenna Array
SP16T Using SPDT in SeriesSP16T Using SPDT in Series
Hittite SPDT (SMT))
DC - 14.0 GHz
SP4T MeasurementsSP4T Measurements
Frequency Range: 7 to 13 GHz
IL: - 4dB with flatness: +/-1dB
Isolation : <- 40dB
Test Fixture DesignTest Fixture Design
Top Side Bottom Side
RF LayoutRF Layout
Frequency Range: 9 to 13 GHz
IL: - 8dB with flatness: +/-2dB
Isolation : <-45dB
Switching Time: < 50ns
Driver LogicDriver Logic
Pulse GeneratorPulse Generator
Simulation & Measurement Simulation & Measurement Results of Pulse GeneratorResults of Pulse Generator
77 78 79 80 81 82 83 84 85 8676 87
0
2
4
6
8
10
-2
12
time, nsec
var(
"TR
AN
.V!"), V
0.5 1.0 1.5 2.00.0 2.5
-30
-20
-10
-40
0
freq, GHz
dBm
(fs(
var(
"TR
AN
.V!"))
)
Pulse Width:
Adjustable 400ps - 1ns
Rise Time: 50ps
Fall Time: 50ps
Bandwidth: up to 2GHz
Solutions for DAQ System
UWB Sampler: for hand-held portable model
PCI Digitizer: for ground vehicle based system
Oscilloscope: for experimental system
ADC Chip: for hand-held portable model
See-Trough-Wall Radar Experiment
Measurements without Wall
Measurements with Drywall
Targets Location
12cm X 24cm
20cm X 24cm
Concrete Wall
Metal-covered Door Targets
Radar Position
Top View -- Hallway Geometry and UWB Radar Setup
2.85m
9.30m
1.02m
Side Wall
Door 1 Door 2
Cylindrical Target
Door 1
Gas Tank
Door 2
Side Wall
Non-through-Wall Image
Image of Water Cup ----- Position 1
Water Cup
Door 1
Door 2
Side Wall
10cm X 12cm
Water Cup
Door 1
Door 2
Side Wall
Image of Water Cup ----- Position 2
10cm X 12cm
CFDTD Simulation
120cm
CFDTD Simulation ParametersMesh SizeNx = 330, Ny = 430, Nz = 330Cell Sizedx = dy = dz = 1.0cmTime resolutiondt = 19.15 ps
Local point source
Drywall boards thickness = 2cmEpson=2.4, Sigma=0.003
Free space gap 6 cm
Concrete @ f = 2 GHzEpson=7.0, Sigma=0.005
z
yx
240cm
Side View
Current simulation Problems
At f=2 GHz =15 cm requiring step size of 1cm.
To increase Mesh Resolution, we needed higher frequency Operation i.e. more mesh points.
Currently with a 4-processor server it requires 5 hours @ 2 GHz-at 4 GHz, it is anticipated 5x23 hours !!!-at 8 GHz it will be 5x26 hours.
1
16
Local point source
16-Elementreceiver array
250cm
350cm
12cm
Z = 120 cm
x
yz
30cm conducting cubic box at (x=70cm,y=195cm,z=120cm)
30cm conducting cubic box at (x=145cm,y=355cm,z=120cm)
55cm
Top View
Radiated UWB Pulse
Baseband signal is Gaussian with 0.8 GHz bandwidthCarrier is 2 GHz Sine Wave.
Recorded Response at 16 Receivers
Reflection from 1st Target
Direct Transmission from source to receivers
Reflection from 2nd Target
(m)
Without Gating
Direct Transmission from Source to Receivers
12 cm: Receiver Spacing
(m)
Direct Coupling Due to the Isotropic Point Source
Reflection from Targets
Reflection from 1st Target
Gating Direct Transmission
Reflection from 2nd Target
(m)
Reflection from far wall
After Gating of receivers response due to direct coupling
Extracted I/Q Channel
I Channel
Q Channel
1st Target
2nd Target(m)
Far wall
Image Recovered from Simulation Data
16
30cm conducting cubic box at (x=70cm,y=195cm,z=120cm)
30cm conducting cubic box at (x=145cm,y=350cm,z=120cm)
Future Work
Digital Signal Processing
Comparison of 2-D Spectral Estimation Techniques for Imaging Synthetic Point Scatterers
Image-Domain TCR is 13 dB
True Points
MVM
ARLP (2 quad)
Pisarenko
PML Estimates
MUSIC
TKARLP (2 quad)
TKARLP (all pred)
Taylor –35 dB n = 5
EV
SVA
2 Super SVA, Taylor
Sinc
RRMVM
ASR
2 Super SVA, SVA
0 dBRelative dB scale –60 dBNote: S.R. DeGraaf, “SAR Imaging…,”
IEEE T-IP, Vol. 7, No. 5, 1998
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