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Development of SAR-based UWB S ee-Through-Wall Radar

Development of SAR-based UWB S ee-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

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Development of SAR-based UWB S ee-Through-Wall Radar

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  1. 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

  2. Outline • Background Information • Electromagnetic/Antenna Aspects • UWB Components Design/DAQ Aspects • Imaging Processing Aspects • See-Thru-Wall Experiment • Future Work

  3. See-Thru-Wall Goals • 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 Tactical Operation Search Operation

  4. 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

  5. Microwave Imaging • Good scene recognition • Poor object recognition • Advantages • Day/night, all weather • Penetration (e.g. buildings) • Disadvantages • Non-literal imagery

  6. Imaging Fundamentals • Optical Images • Angle vs. Angle • Microwave Images • Range vs. Angle Range Angle Angle Crossrange

  7. Optical Quality at Radar Frequency

  8. Interior Image of Mannequin Mannequin Behind Wall Photograph Mannequin Only

  9. Resolution vs. Frequency

  10. 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)

  11. See-Through Wall Radar Prototype RF Transceiver DAC/Control Image Processing Wall Radar Rage:20 m Radar PRF: 5 MHz Pulse Width: 0.5 ns Center Frequency: 10 GHz Hand-held portable/Ground Vehicle-Based System

  12. Electromagnetic/Antenna Aspects of the 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

  13. UWB Transceiver Design and Data Acquisition Aspects • UWB components design: power amplifier, low noise amplifier, power divider, SP16T switch, mixer, pulse generator. • Sampling of UWB signal: equivalent time sampling technique

  14. 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

  15. 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

  16. Propagation Modeling • Frequency domain measurement • VNA for insertion transfer function. Advanced Design System (ADS) models

  17. UWB Antenna Consideration • Wide band-width • Good impedance match • Minimum waveform ringing • Minimum pulse dispersion • Small size • Low cost

  18. TypesofUWB 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

  19. Antipodal Vivaldi Antenna • Developed by Gibson in 1979 • Wide band performance • Fabricated on dielectric substrates • Great potential to low cost and weight • Small size Tapered flares on different layers Dimension:2.15cm x 5.52cm Substrate:Roger 4003C, 10 mil-thick

  20. Vivaldi Sub-array • 16 Element sub-array • Dim: 18 cm x 40 cm • Wilkinson power divider • Element spacing: 2.15 cm 7.5 GHz – 12.5 GHz

  21. Pattern: Simulation Versus Measurement @ 10 GHz Measurement:13dB Gain, 4° Beamwidth Simulation: 15dB Gain, 3° Beamwidth

  22. Measured Radiation Pattern E Plane H Plane

  23. Transmitter/Receiver Structure 1 2 3 4 16 ........ Switch

  24. System Block Diagram

  25. UWB See-Through-Wall Imaging RadarSimulation (in ADS)

  26. 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.

  27. UWB_SubHarmonic_Mixer Simulation

  28. 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

  29. 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.

  30. DRO Simulation

  31. 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

  32. 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

  33. 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

  34. UWB System Topology

  35. SP16T With Antenna Array

  36. SP16T Using SPDT in Series Hittite SPDT (SMT) DC - 14.0 GHz

  37. SP4T Measurements Frequency Range: 7 to 13 GHz IL: - 4dB with flatness: +/-1dB Isolation : <- 40dB

  38. Test Fixture Design Top Side Bottom Side

  39. RF Layout Frequency Range: 9 to 13 GHz IL: - 8dB with flatness: +/-2dB Isolation : <-45dB Switching Time: < 50ns

  40. Driver Logic

  41. Pulse Generator

  42. Simulation & Measurement Results of Pulse Generator

  43. Pulse Width: Adjustable 400ps - 1ns Rise Time: 50ps Fall Time: 50ps Bandwidth: up to 2GHz

  44. Solutions for DAQ System UWB Sampler: for hand-held portable model Oscilloscope: for experimental system PCI Digitizer: for ground vehicle based system ADC Chip: for hand-held portable model

  45. See-Trough-Wall Radar Experiment

  46. Measurements without Wall

  47. Measurements with Drywall

  48. Targets Location 20cm X 24cm 12cm X 24cm

  49. Top View -- Hallway Geometry and UWB Radar Setup Concrete Wall 9.30m Radar Position Side Wall 2.85m Door 1 Door 2 1.02m Targets Metal-covered Door

  50. Non-through-Wall Image Side Wall Door 2 Gas Tank Door 1 Cylindrical Target

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