Experimental Results of SAR Imaging Using a Low-Cost X-band Radar with a PLL with Direct Modulation for UAV Applications

This paper presents the system design, imaging algorithm, and first trial results of an X-band frequency modulated continuous wave Synthetic Aperture Radar (SAR) with the transmitted waveform synthesized by a Phase Locked Loop (PLL) with direct modulation. The rapid growth of autonomous vehicle technology puts a demand on sensors, precision, and affordability. The latest navigation and avionics trends lead to miniaturization, highly appreciated in Unmanned Aerial Vehicle (UAV) applications. In particular, low cost, small size, and high precision of remote sensors find a wide range of applications in civilian and military domains (e.g., autonomous delivery systems, driving assistance systems, self-driving cars, military surveillance missiles, or fire guidance, among others). The SAR sensor presented in this paper was designed to be a small and affordable radar sensor dedicated to small UAV platforms and radar imaging. System architecture and a brief description of the signal processing algorithms are illustrated in this paper. The utility of the system is supported by preliminary results from ground-based and airborne trials.