Multi-Band Radar Based on a Cavity-Less Ultra-Short Optical Pulse Source for Simultaneous Measurement of Distance and Velocity

A flexible multi-band radar is proposed for simultaneous measurement of distance and velocity, based on a cavity-less ultra-short optical pulse source (CUOPS). At the transmitter, through sampling of an intermediate-frequency linear frequency modulation waveform (IF-LFMW) via the CUOPS, multi-band radio-frequency linear frequency modulation waveform (RF-LFMW) signals can be successfully generated. Meanwhile, the multi-band echo signals are de-chirped to the IF band through the mixing with the optical RF-LFMW reference signals at the receiver. When a multi-band RF-LFMW signals covering C- to Ka-band are experimentally generated, the distance measurement of static targets is achieved with both error and resolution of 0.48 cm and 30 cm, respectively. Moreover, because of the different scattering characteristics of the target at various frequency bands, simultaneous detection of multi-band RF-LFMW signals is beneficial for reducing the possibility of false target detection. Next, simultaneous distance and radial velocity measurement without ambiguity can be achieved by the use of dual-band RF-LFMW signals with opposite chirp. Both a range of 40 km and a velocity of 400 m/s are numerically verified. The most prominent advantage of the proposed scheme lies in that the operation bands can be flexibly tuned by varying the frequency of the local oscillator microwave signal at the CUOPS. Hence, the proposed scheme is promising to realize a flexible photonic-assisted multi-band radar for anti-stealth detection application.