Transmitter and Receiver Design at L-band and X-band for FM-CW Radar Altimeter

In recent years, there has been a growing interest in FM-CW (frequency modulated continuous wave) technology for military and civilian applications. FM-CW radar altimeters find applications to detect ground proximity during automatic landing in low-visibility condition, collision avoidance systems in vehicles, and ground penetrating radars for buried object detections such as landmines, pipelines, etc. The development of a low-power L-band and X-band FM-CW radar hardware and design of a third order loop filter for the phase locked loop (PLL) are the main focus of this paper. We provide detailed circuit description of PLL-VCO and third order loop filter for direct digital synthesis (DDS) based FM-CW generation. Results of laboratory trial for the calibration of FMCW radar hardware are presented to demonstrate the feasibility of operation at X band. All test results on actual radar hardware at X-band are described in the paper.