Noise Analysis for Six-Port Radars with Schottky Diode Detectors

Six-port continuous-wave radar systems have been used for vibration analysis in predictive maintenance and vital sign sensing applications. A core component of these systems are microwave power detectors as down-converters. This paper investigates a passive Schottky diode detector regarding its noise behavior. Therefore, diode noise measurements are presented to determine the flicker noise parameters. Based on the derived detector noise behavior, the theoretical precision limit of continuous-wave radar systems is derived and compared to measurements of a prototype at 24 GHz. A measurement precision of 1 ┬Ám could be achieved at a baseband bandwidth of 100 Hz and using a metallic target at a distance of 1 m.