Bistatic forward-looking SAR imaging of a runway using a compact receiver on board an ultralight aircraft

Bistatic synthetic aperture radar (SAR) enables high resolution imaging in forward direction of a moving receiver, if the motion of the transmitter guarantees an adequate aspect angle variation with respect to the scene center. Such a configuration could be realized at an airport, where a ground-based transmitter illuminates the runway and the receiver on board an aircraft receives the reflected signals and provides the pilot with a high-resolution radar image of the runway. The situational awareness and the safety of approaching aircrafts in conditions of low visibility could be increased using such a system. A big challenge is the time and phase synchronization of the transmitter and receiver for coherent processing. The synchronization method as well as the hardware setup of the ground-based transmitter and the compact X-band receiver are presented in this paper. Several experiments to demonstrate the feasibility of imaging a runway during the landing approach were performed using a receiver on board an ultralight aircraft and a transmitter on a moving truck to illuminate the runway. First image results are presented.