Metasurface Aperture Design for Far-Field Computational Microwave Imaging Beyond Rayleigh Diffraction Limitations

Improving the resolution of metasurface apertures (MAs)-based computational microwave imaging (CMI) is of great significance for its practical application. Existing MAs-based CMI (MAs-CMI) has limited resolution due to the limited size of MAs, the so-called Rayleigh diffraction limit (RDL), and must rely on complex back-end algorithms to achieve far-field super-resolution imaging. In this article, a single-frequency (10 GHz) single-sensor double-layer transmitarray (DTA) is designed to improve the resolution of MAs-CMI from the hardware aspect, which consists of a horn as feed, a layer of passive MA (PMA), and a layer of dynamic MA (DMA). By carefully designing the structure of the DTA, a variety of far-field random radiation patterns beyond RDL can be obtained, and the imaging resolution of the MA-CMI can be effectively improved. Simulation and measurement results show that the resolution of the far-field radiation patterns of the proposed DTA is at least 1.56 times that of RDL at the same aperture. Finally, an imaging experiment based on a manufactured DTA is performed to further demonstrate its far-field super-resolution characteristic for CMI. This is the first time that the far-field super-resolution TA based on MAs for CMI is reported.