Low profile dual-band antenna loaded with artificial magnetic conductor for indoor radar systems

A dual-band antenna is designed for a fall-detection radar and telemetry system. The radar is designed based on the stepped frequency continuous wave (SFCW) concept, which requires Ultra Wideband (UWB) operation, low inter-element coupling and a directive radiation pattern with low backlobe. The telemetry system uses the 2.45 GHz band to enable signal transmission/reception in an indoor environment and the 6-7.5 GHz band for radar sensing part. A main dual-band radiator with a slotted patch is used as the basis for the antenna design: the patch resonates at 2.45 GHz whereas the antenna slot enables a wide band operation for the radar system. To enable a low-profile, an artificial magnetic conductor (AMC) structure is integrated into the antenna. It works as a perfect magnetic conductor (PMC) plane from 6 to 7.5 GHz and can be located close to the slot antenna functioning as a reflector. Both numerical and experimental results indicate a satisfactory antenna performance in terms of reflection coefficient and radiation pattern. The antenna was also integrated into the radar system and tested in a real environment on three subjects at fixed distances. A fall-detection up to 6 meters was achieved.