Single-Receiver Space–Time Coding Antenna Array With Stepped-Frequency Synthesis for Ultrawideband Radar

In recent years, space–time coding metasurfaces and antennas have attracted widespread attention in both radar and sensing technologies due to their low manufacturing costs, simple architecture, and the ability to eliminate reliance on numerous transmit–receive (TR) components, demonstrating significant application potentials. Nonetheless, their signal bandwidths are usually constrained by the modulation rate of control circuit and response speed of tunable components, greatly limiting the signal resolution. To improve the resolution of radar and sensor systems based on the space–time coding metasurfaces and antennas, here we propose a high-precision radar system with stepped-frequency continuous wave (SFCW) signal and space–time coding antenna array. By combining the SFCW, the proposed space–time coding radar system can synthesize broadband signals from narrowband instantaneous signals, solving the problem of space–time coding antenna in processing broadband signals. An ultrawideband radar system is constructed based on the space–time coding antennas, which can replace traditional multichannel Tx/Rx phased arrays. By using the designed orthogonal codes, signals from all array elements can be recovered with only one receiver, thereby enabling a single-channel system with reduced hardware complexity. The measured results show that the system has a synthetic bandwidth of 2 GHz and achieves range accuracy of 0.0511 m and angular accuracy of 0.832°. Compared to the conventional ultrawideband high-precision radars, the proposed radar system offers lower system complexity and hardware costs, while maintaining high range and direction accuracy.