Abstract-Terahertz Bistatic Synthetic Aperture Radar for 1-D Near-Field High-Resolution Imaging

Li Ding, Yangyang Ye, Guoyao Ye, Yiming  Zhu,

https://link.springer.com/article/10.1007%2Fs10762-018-0530-2

Considering the difficult transceiver-isolation problem of the monostatic synthetic aperture radar (SAR) in the terahertz (THz) band, this paper proposes a compact THz bistatic SAR (BiSAR) geometry. The system allows the separately distributed transmitter and receivers. At the receiving end, there are a direct-wave receiver and an echo receiver, both operating at the heterodyne and in-phase mode. The echo receiver runs along a linear rail to fulfill the scene scanning, while the direct-wave one is fixed as a reference. Furthermore, assuming that the receivers are synchronized, both the problem of synchronization between the separated transmitter and receivers and the problem of timing at the signal acquisition would be solved by utilizing the high coherence between the echo and the direct wave. Based on such a system, the application of THz BiSAR for one-dimensional imaging is taken into consideration. Then, a high-resolution imaging algorithm is proposed benefitting from the total least squares estimating signal parameters via rotational invariance techniques (TLS-ESPRIT) and the spatial smoothing process (SSP). The imaging performance is then demonstrated by both simulations and the experiments in the 0.183 THz.

Abstract-Bistatic Synthetic Aperture Radar With Undersampling for Terahertz 2-D Near-Field Imaging

Li Ding,  Yangyang Ye, Guoyao Ye,   Xiwang Wang, Yiming Zhu

http://ieeexplore.ieee.org/document/8252790/

To avoid the difficult transceiver-isolation problem of a monostatic synthetic aperture radar (SAR) for terahertz (THz) near-field azimuth-range imaging, a compact bistatic SAR geometry is demonstrated in this paper. The system consists of one fixed transmitter, one moving echo receiver and one fixed direct-wave receiver. The transmitter emits wideband signals for range resolution, and the echo receiver moves along a designed trajectory for the cross-range resolution, and the direct-wave receiver is taken as a reference for synchronization. Since the wavelength of THz is in the order of millimeter or submillimeter, the requirement on subwavelength interval of spatial sampling by the Nyquist theory aggravates the measurement difficulty. To break this limitation, a compressed sensing-based imaging algorithm is presented. Allowing the undersampling both in spatial domain and frequency domain, the proposed algorithm can provide high-resolution performance with few measurements. Thus, the balance between the resolution and the amount of measurements can be made. The system geometry and imaging performance are then demonstrated by both the simulations and the experiments in the 0.178–0.188 THz band.