1. 지반변형 모니터링을 위한 GROUND-BASED SAR 개발 조성준(1), 이훈열(2), 성낙훈(1), 김정호(1)
한국지구시스템공학회
조성준(1), 이훈열(2), 성낙훈(1), 김정호(1)
(1)한국지질자원연구원 지반탐사연구실
(2)강원대학교 지구물리학과

2. Agenda Introduction of SAR and GB-SAR Vector Network Analyzer
Hardware configuration of GB-SAR
SAR Focusing and Interferometry
Feasibility test
Conclusion

3. Radar Radio Detection and Ranging
WW II, US army. Military use
measure backscattered amplitude and distance to target
High power, sharp pulse -> low power, FM-CW chirp signal
Navigation radar
Weather radar
Ground Penetrating Radar
Imaging radar
cf) LIDAR (Light detection and Ranging)

4. Imaging Radar Different Eyes Microwave Ranging Active System
microwave, UHF, VHF
surface roughness and dielectric constant
Microwave Ranging
All-weather
Cloud-free
Side-looking
Active System
Day and night imaging
independent of solar illumination

5. SAR(Synthetic Aperture Radar)
Euro50
Optics : Diameter of the lens or mirror. The larger the aperture, the more light a telescope collects.
2.4m Hubble Space Telescope
10m Keck, Hawaii
16.4m VLT (Very Large Telescope), Chile
50m Euro50 (extremely large T.)
100m OWL (OverWhelmingly Large T.)

6. Real vs. Synthetic Aperture
Real Aperture :
resolution ~ Rλ/L
Synthetic Aperture:
resolution ~ L/2
Irrespective of R

7. Range Compression Linear Chirp Signal Chirp autocorrelation Function
Matched Filtering
For ERS-1/2,
Pulse duration (T): 37.1 s
Bandwidth : 15.5 MHz
Half power width of autocorrelation function: s
Pulse Compression Ratio: 575 (ERS-1/2)
Ground Range Resolution: 12.5 m

8. SAR Focusing – Point Target
azimuth
range
original
After range compression
After migration
After azimuth compression

9. GB-SAR GB-SAR: Ground-Based Synthetic Aperture Radar
Imaging Radar
Azimuth aperture synthesis
Ground-Based
Fairly versatile system configuration
Multiple frequency (L, C, X, Ku, Ka, etc)
Full Polarization (VV, VH, HV, HH)
Ultimate SAR focusing
Zero Doppler centroid (stationary vehicle during Tx/Rx)
Accurate estimation of Doppler rate from geometry
Topography Mapping: Cross-Track InSAR or Delta-K InSAR
Surface Motion: Zero-baseline and short atmospheric path for Temporal Coherency, DInSAR and PSInSAR
Useful for new SAR concept design

10. State of the art of GB-SAR
LISA SAR (Italy)
GB-POLInSAR (Australia)
GB-SAR (Japan)

11. Agenda Introduction of SAR and GB-SAR Vector Network Analyzer
Hardware configuration of GB-SAR
SAR Focusing and Interferometry
Feasibility test
Conclusion

12. Vector Network Analyzer
Agilent 8753ES
Networks are analog circuits, not computer
communication paths.
Testing filters, attenuators, splitters, couplers,
amplifiers, receivers, duplexers, mixers, and many
more device types

13. 네트워크 분석?
Network analysis is the characterization of a device, circuit, or system derived by comparing a signal coming out of the device with a signal applied to the device.
                                                      .

14. Device Characteristics
Transmission Line Theory
Lightwave analogy to high-frequency device characterization
Transmission line concept NOT necessary when:
Wavelength >> wire length
Voltage and current are not dependant on position
Transmission line concept NEEDED necessary when:
Wavelength < 10 times wire length
Voltage and current depend on the position on the line

15. How do we characterize devices?

16. How do we characterize devices?

17. How do we characterize devices?

18. How do we characterize devices?

19. Vector ?

20. Transmission Line Basics
KIGAM

21. Transmission Line Basics
KIGAM

22. Characteristic impedance
Transmission line
Characteristic impedance
KIGAM

23. Why 50 Ohms and 75 Ohms?
KIGAM

24. S-parameters
KIGAM

25. S-parameters Defined
KIGAM

26. Network Analyzer Operation

27. Which Test parameters?
Reflection parameters
Transmission parameters

28. Vector error correction
open
short
Calibration
Error correction
: systematic errors
random errors
drift errors
Measurement system
Starting & ending point
load

29. 벡터 네트워크 분석기를 이용한 GPR KIGAM Measurement of first arrival in time domain
Short antenna : length 41.5 cm
feed line 4 cm
Calculated main freq.=303 MHz
Measurement of first arrival in time domain
KIGAM

30. 벡터 네트워크 분석기를 이용한 시추공 레이더 탐사기
Ramac result
Stepped frequency radar
KIGAM

31. Agenda Introduction of SAR and GB-SAR Vector Network Analyzer
Hardware configuration of GB-SAR
SAR Focusing and Interferometry
Feasibility test
Conclusion

32. GB-SAR System(KIGAM-KNU)

33. System Configuration

34. VNA(Vector Network Analyzer)
Stepped frequency
Both of Tx and Rx
Flexibility

35. Antenna H-Pol radiation pattern Dual-Polarimetric Square Horn Antenna
Frequency(GHz)
5.0~5.6
Beam Width
E-Plane(deg)
15(nominal) 
12.1~13
H-Plane(deg)
15(nominal)
15.5~17.5
Gain(dBi)
20(nominal)
20.5 min.(20.5~21.8)
VSWR
1.5 max.
1.4 max.
Isolation
35dB 이하
50dB 이하
Weight(kg)
4 max.
3.1 max.
Input Impedance(Ω) 50
50 

36. Rail and motion control
6m rail (2m X 3)
Home and limit switch
Micro step motor
측정장치 일체형
NI motion controller

37. Amp and RF switch Operating Freq.: 2~6 GHz Power Gain: 34 dB
Maximum input: 6 dBm
Operation Freq.: ~20GHz
GPIB interface
3중 1X2 SPDT

38. Acquisition software Callibration Start Initialize all system
Move to start position
Acquisition
Call cal:VV:Switching:
Call cal:VH:Switching:
Call cal:HV:Switching:
Call cal:HH:Switching
Save data
Move or Stop
End

39. SAR Focusing Algorithms
Advantage
Disadvantage
Usage
Range-Doppler or ω-k
Widely used for SAR
Memory inefficiency for partial-focusing
Near Range
(full-focusing)
Deramp-FFT
Efficient in memory and CPU time
Distortion in near range
Far Range
(partial-focusing)
Time Domain
Exact everywhere
Time consuming
Everywhere

40. GB-SAR Resolutions Range resolution: (a) Full Focusing
(b) Partial Focusing

41. GB-InSAR Configuration
DInSAR
Cross-Track InSAR
Delta-K InSAR
Cross-Track and Delta-K InSAR
DInSAR with range change
Cross-Track InSAR

42. KIGAM Test T1 Range: Center frequency=5.3GHz Bandwidth=200MHz
Sample=1601
Power=33dBm (2W)
Azimuth:
Scan length=5m
Step=5cm
Sample=101
T2: Temporal baseline of 20minutes (DInSAR)
T3: Spatial baseline of -30cm vertical (InSAR DEM)
T4: Frequency shift of -10MHz (Delta-K InSAR)

43. Image Area

44. VV

45. VH

46. DInSAR (T2-T1) VV

47. Automatic Acquisition with 2cm Step, 2007. 3. 19 7:22pm- 4:20am, A1~A9HH VV

48. Measurement of Target Displacement 2007. 7. 18

49. Movements of the reflector (150m away from the system)
↑ Radar direction
A trihedral corner reflector on top of an acrylic plate with rulers on both sides
Displacement from the origin:
1, 2, 6, 10, 30, 40mm

50. Comparisons – Original (ground range)HH VV VH HV

51. Comparisons – Original (slant range)HH VV VH HV

52. Comparisons – After system correctionHH VV VH HV

53. Conclusion
A GB-SAR system was developed, tested, and waiting for applications.
Optimal GB-SAR focusing algorithms were tested.
Cross-Track and Delta-f InSAR were tested.
DInSAR tested: Phase stability of 1° (0.1mm range) was achieved for several hours for stable reflectors, rendering phase change of 10 ° to be assured (1mm accuracy).
PSInSAR displacement measurement: R2= achieved.
GB-SAR can be used for various applications such as:
Safety monitoring of natural or anthropogenic structures
Microwave backscattering properties of target
New SAR system concept design
More robust GB-SAR system optimized to a specific application will be developed.

54. Thank You, and Welcome to Korea.

55. Conclusion
A GB-SAR system was developed, tested, and waiting for applications.
Optimal GB-SAR focusing algorithms were tested.
Cross-Track and Delta-K InSAR were tested.
DInSAR or PSInSAR were tested: Phase stability of 1° (0.1mm range) was achieved for several hours for stable reflectors, rendering phase change of 10 ° meaningful (1mm range accuracy for DInSAR).
GB-SAR can be used for various applications such as:
Safety monitoring of geohazard area
Safety monitoring of artificial structure
Microwave backscattering properties of target
New SAR system concept design
More robust GB-SAR system optimized to a specific application will be developed.->accurate positioning, cost effective system