A Distance-Compensated Radar Sensor with a Six-Port Network for Remote Distinction of Objects with Different Dielectric Constants

Abstract

A distance-compensated radar sensor with a six-port network is proposed and successfully implemented to remotely discriminate target objects with different dielectric constants. The sensor simultaneously measures distance and reflection coefficients of the objects using DC output voltages of the six-port network, thereby obtaining a comparative profile of their dielectric constants with distance compensation scheme. The distinction of the target's dielectric constant profile is theoretically derived and experimentally demonstrated within a target distance of 1 m using a 24 GHz six-port radar sensor module. The die size of the six-port network MMIC is 2.0 × 1.8 mm², and the whole sensor module is realized in 3.6 × 5.5 cm² , excluding a horn antenna and signal source.