Low-Profile Broadband 1-Bit Randomly Encoded Folded Reflectarray Co-Aperture Transceiver for Frequency-Diverse Microwave Imaging

In this letter, we propose a low-profile broadband 1-bit randomly encoded folded reflectarray co-aperture transceiver for frequency-diverse microwave imaging. The system consists of a broadband polarization conversion metasurface, a polarizer grid, and a dual-polarized horn. The designed metasurface exhibits a high polarization conversion ratio above 90% and a broad operational frequency band of 13 GHz to 31 GHz (corresponding to 82% relative bandwidth), which is much wider than the state of arts. By combining a polarizing grid and a polarization converter, the feed optical path of the transmitter can be folded. So the overall thickness of the system is reduced by half in comparison to traditional reflective or transmissive metasurface imaging systems. Furthermore, we integrate the transmitting and receiving antennas into a single dual-polarized antenna for feed. Real-time microwave imaging examples are provided to demonstrate the high performance of the folded reflectarray co-aperture tranceiver. The proposed system may find wide applications in real-time tracking of objects in integrated sensing and communication.