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.
Abstract-Flexible antennas in radar applications enable the user to go around obstacles or detect targets at hidden places. In this paper, two elliptical lenses of different size made of high density polyethylene and stacked on a flexible dielectric waveguide are designed and measured from 140 GHz to 180 GHz. The feeding dielectric waveguide and the mode transition from metallic waveguide to dielectric waveguide was investigated with full wave simulations. The elliptical lenses were designed with a geometrical optics approach. The realized antennas have a gain larger than 24 dBi and 27 dBi and a maximum side lobe level below −15.8 dB.
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