Photonics-based multi-band/multi-mode radar signal generation

Microwave/millimeter-wave photonics is playing a prominent role in overcoming the challenges of RF signal generation and processing. This evolving technology has many advantages, such as RF carrier stability and broad operating bandwidth, and is applicable to a wide range of civil and military applications such as 5G communication networks, radar/jammer systems, and medical imaging. In this work, we leverage the multidimensional capabilities of microwave photonics in order to generate multi-band/multi-mode radar signals for multi-purpose applications. Our proposed system can generate up to five radar bands, simultaneously, with different modulation bandwidths, without hardware modifications. Additionally, various radar waveforms can be transmitted, simultaneously, over the corresponding radar bands. The RF radar signals are generated optically using a reconfigurable frequency comb source, which reduces the system cost significantly. The stability of the RF carriers is experimentally tested and compared with that of the mode-locked-loop-based laser sources, wherein a comparable performance is observed. Experimental results show the generation of four radar waveforms, including frequency modulated waveforms (pulsed linear frequency modulation and frequency modulated continuous wave) and polyphase codes (Barker-11 and Barker-13). Moreover, five carrier frequencies are used to transmit the various radar modulation schemes. These are 5.25, 9.325, 16.1, 26.4, and 28.15 GHz RF carriers. The signal quality is measured experimentally, and high signal-to-noise ratio (SNR) of 35, 30, 30, 25, and 20 dB SNR was observed in the C-, X-, Ku-, K-, and Ka-bands, respectively.