2015 Fiscal Year Research-status Report
Detection of Buried Objects by Synthetic Aperture Radar Imaging for Improved Disaster Response
| Project/Area Number |
15K18075
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| Research Institution | Tohoku University |
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Principal Investigator |
KOYAMA CHRISTIAN 東北大学, 東北アジア研究センター, 産学官連携研究員 (40704961)
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| Project Period (FY) |
2015-04-01 – 2017-03-31
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| Keywords | GB-SAR / GPR / Polarimetry / Disaster mitigation / Radar imaging / Target detection |
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| Outline of Annual Research Achievements |
1) Large type Vivaldi antennas were designed and simulated by using CST Microwave Studio. Antennas were fabricated by printing on PCB substrate and soldering high-frequency connectors. The antennas were tested in the anechoic chamber and antenna characteristics were measured for the later signal processing. Using the polarimetric antenna array with a 4-channel VNA, first in-door tests and experiments with subsurface targets were carried out in the sand pit. Based on measurements in the anechoic chamber and sand pit, optimization of the system parameters and polarimetric calibration were performed.
2) Different sized and shaped radar reflectors were manufactured, including simple flat plates, dihedral and trihedral corner reflectors. The reflectors were installed below ground in different soil types at different locations. The most suitable locations in the study area were selected based on multi-temporal SAR data analysis using the archived airborne SAR images. The in-situ soil permittivity at the time of the ALOS-2, Pi-SAR2 and Pi-SAR-L2 data acquisitions was recorded by using TDR sensors. CMP data was acquired by GPR antennas to measure the vertical permittivity variations in the subsurface.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The work is progressing rather smoothly and principally all the tasks scheduled for the first year could be accomplished. The amount of computer simulations and testing in the anechoic chamber had to be reduced slightly due to time constraints. Moreover one of the scheduled airborne SAR campaigns had to be canceled due to a system failure of the NICT Pi-SAR2 X-band sensor. Apart from that no major changes or shortcomings in the proposed plan had to be taken into account. The installation of the subsurface target went smoothly thanks to the help of cooperation partners and Tohoku University students. However, it was found that improvements in the clutter reduction might be an important additional issue in order to obtain better target detection performance in GB-SAR images. Related literature studies consumed some amount of extra time.
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| Strategy for Future Research Activity |
The developed GB-SAR system will be used for experiments with buried subsurface corner reflectors in the field. Additional small corner reflectors will be build and installed at an intensive test site. GB-SAR images will be acquired with different system parameter settings. The soil permittivity will be changed by wetting the soil. Bistatic groundborne/airborne SAR experiments and bistatic groundborne/spaceborne experiments will be carried out in which the GB-SAR system will act as receiving polarimetric antennas only while the incoming polarimetric signals will be transmitted by the airplane and satellite based antennas, respectively. This data will be used to investigate the potential to detect subsurface objects from bistatic SAR configurations. Based on electromagnetic reflection and transmission theory combined with the large data base of experimental data and state-of-the-art polarimetric SAR images, semi-empirical algorithms to detect and localize persons and objects buried below ground will be developed and tested. A new focus will be on the improvement of clutter reduction in the GB-SAR images.
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| Causes of Carryover |
The research was carried out effectively and the small incurring amount has occured.
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| Expenditure Plan for Carryover Budget |
The incurring amount will be used to purchase a notebook PC for in situ measurements and outdoor GB-SAR experiments.
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Research Products
(10 results)
