Variable-resolution SAR Imaging System Based on Coding Metasurface Antenna

In order to meet different resolution requirements for different kinds of scenes, here a new SAR mode of operation named variable-resolution (VR) SAR is proposed, which involves diverse radiation pattern and dinstinct pulse repetition frequency (PRF) to realize a continuously agile resolution in azimuth direction. It borrows the principle of spotlight SAR that azimuth resolution is derived from corresponding synthetic aperture length and observation angle, namely every azimuth sampling point develops different beam pattern to illuminate certain region due to the synthetic aperture distributions in this system. Optimization of PRF has been conducted to obtain a relative larger swath width and a lessened sample data storages by making resolution of some unimportant and unconcerned details decline under the premise of no azimuth ambiguities. Driven by its specific properties, coding metasurface antenna is utilized to generate desired diverse pattern in real time, making VR SAR possible in practice. There are two potential advantages of the proposed imaging mode: 1) offers the higher resolution and larger image sizes than would otherwise be possible in stripmap and spotlight SAR modes and 2) reduces the pressure of data storages and brings a high imaging efficiency. The mathematical model of VR SAR system is bulit up and the feasibility is demonstrated through a series of simulations, as well as metrits. This VR SAR opens a new venue for earth observation, space-borne remote sensing and related SAR images processing, heading for agile frequencies, bandwidth and beyond.