Multipath modelling in a dual-frequency phase-comparison FMCW radar

The unique configuration and application of the Active Protection System (APS) radar sensor, developed by Reutech Radar Systems, requires the development of a novel multipath interference model. This paper derives a mathematical model for the effects of specular multipath interference (primarily due to ground reflections) on the received signals of a dual-frequency phase-comparison FMCW radar. Two formulas are derived, one describes the change in amplitude and the other describes the change in phase due to specular multipath. This has interesting and previously unknown effects when Range-Doppler processing is applied to the corrupted input signal. Simulation results and measurements are presented to corroborate the theory.