Radar Receiver with Intrinsic Power Limiter Assisted by Microwave Photonics

This article presents an approach of a radar receiver that has an intrinsic power limitation based on photodetector power saturation. The radar signal power detection is implemented using optical self-homodyne detection. The proposed architecture uses a phase modulator (PM) to modulate the optical carrier and a fiber Bragg grating (FBG) to filter the spectrum and convert the phase to intensity modulation. The self-homodyne technique eliminates the optical carrier influence. It enables to reduce of shot noise influence and increases the photodetected optic power to improve the conversion gain. Moreover, the photodetection is performed at the radar pulse baseband, allowing to obtain transimpedance gain. An experimental demonstration is performed. A dynamic range of 56 dB is achieved for a pulsed radar operating at 20 GHz.