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

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.