A New Single-Pass SAR Interferometry Technique with a Single-Antenna for Terrain Height Measurements

One of the prospective research topics in radar remote sensing technology is the methodology for designing an optimal radar system for high-precision two-dimensional and three-dimensional image acquisition of the Earth’s surface with minimal hardware requirements. In this study, we propose a single-pass interferometric synthetic aperture radar (SAR) imaging technique with only a single antenna for the estimation of the terrain height. This technique enabled us to obtain terrain height information in one flight of the carrier, on which only one receiving antenna was mounted. This single-antenna single-pass interferometry required a squint angle look geometry and additional image synthesis processing. The limiting accuracy of the terrain height measurement was approximately 1.5 times lower than that of the conventional two-pass mode and required a longer baseline than two-pass interferometry to have an equivalent accuracy performance. This imaging method could overcome the temporal decorrelation problem of two-pass interferometry due to a short time gap in the radar echo acquisitions during two sub-aperture intervals. We compared the accuracy performance of the terrain height measurements of our method with the conventional two-pass interferometry. This comparison was carried out at various spectral bandwidths, degrees of surface roughness, and baseline lengths. We validated our idea with numerical simulations of a digital elevation map, and showed real extracted data of the terrain heights in the Astrakhan and Volga regions of the Russian Federation, obtained from airborne SAR with our single-antenna single-pass interferometry technique

Study on THz Imaging System for Concealed Threats Detection.

PhD ThesisMany research groups have conducted studies on Terahertz technology for various applications in the last decades. THz imaging for personnel screening is one prospective application due in part to its superior performance compared with imaging microwave bands. Because of the demand for the accurate detection, it is desirable to devise a high-performance THz imaging system for concealed threats detection. Therefore, this thesis presents my research on the low-cost THz imaging system for security detection. The key contributions of this research lie in investigating the linear sparse periodic array (SPA) THz imaging system for concealed threats detection, improving the traditional reconstruction algorithm of Generalized Synthetic Aperture Focusing Technique (GSAFT) to suppress the ghost images and applying the compressive sensing technique into the proposed SPA-THz imaging system to reduce the sampling data but maintain the image quality. The first part of the work is to investigate the linear sparse periodic array (SPA) and its configuration with large element spacing in simulation, deriving the design guideline for such a SPA THz imaging system. Meanwhile, the improved GSAFT reconstruction algorithm and multi-pass interferometric synthetic aperture imaging technique have been proposed to suppress the ghost image and improve the image quality, respectively. Secondly, the compressive sensing technique has been investigated to reduce the sampling data. Therefore, we have proposed the corresponding discrete CS SPA-THz reconstruction model and verified it in simulation. Finally, we have devised a simplified experimental set-up to assess the practical imaging performance, verifying the proposed SPA-THz imaging system. The set-up only uses 1 Tx and 1 Rx scanning on two separate tracks to effectively realize the proposed imaging system. The reconstructed images by the GSAFT and CS approaches with the measured data have both shown good consistency with the simulated results, respectively. And the multi-pass interferometric synthetic aperture imaging has been experimentally proved effective in improving image SNR and contras