Dual-functional microwave photonic system for concurrent radar and secure communication via radar signal masking

Integrating functions such as radar and communication into a single system is of great significance for the miniaturization and functional integration of future electronic warfare and 6G systems. Here, we show a dual-functional microwave photonic system for concurrent radar and secure communication. The scheme utilizes microwave photonic frequency multiplying and frequency conversion techniques to shift both the intermediate frequency radar and communication signals to the same frequency band, enabling radar and communication operations at the same time and frequency. The high-power radar signal is also used to mask the communication signal, increasing the difficulty of signal interception and thus enhancing security. By employing de-chirping at the radar receiver and self-interference cancelation at the communication receiver, the radar function can be implemented and the communication signal can also be correctly demodulated after removing the radar masking. An experiment is performed. A 0.3-GHz bandwidth linearly frequency-modulated signal is quadrupled and superimposed with two up-converted 0.5-Gbaud orthogonal frequency-division multiplexing signals. A communication data rate of 2 Gbit/s, a radar ranging measurement error of less than $\pm$ 0.3 cm, and a radar inverse synthetic aperture radar imaging resolution of 12.5$\times$10.2 cm are achieved.