A 160-GHz Radar With Flexible Antenna Used as a Sniffer Probe

In radar measurements, the observed area is limited by the antenna beamwidth, and due to the usually fixed transceiver position, only unhidden targets in a small observation area can be detected. Furthermore, bulky lens dimensions prevent the use of radar systems in constricted surroundings despite the small dimensions of microwave monolithic integrated circuit (MMIC) radars. To avoid this issue, a new system concept for a flexible and low-cost 160-GHz radar sniffer probe is presented. The flexible sniffer probe is an extremely low-loss dielectric waveguide with a dielectric elliptical lens (28 dBi) at the end. The dielectric waveguide has dielectric losses of 4.5 dB/m at 160 GHz and high flexibility, supporting bending radii of 1.5 cm with negligible losses. To feed the dielectric waveguide, a metallic waveguide with a duplexer is used, which is fed by a special MMIC-to-metallic waveguide transition. The proposed system expands the known radar measurement scenarios with new industrial, medical, and security applications.