Compact directional UWB antenna with dielectric insert for radar distance measurements

A circular waveguide-fed UWB antenna for the frequency range from 8.5 to 10.5 GHz is presented, incorporating a dielectric insert mounted inside a short metallic excitation horn, yielding a significantly enlarged aperture efficiency compared to the same horn without dielectric insert and even to the theoretical limit of a conical horn antenna of infinite length having similar geometrical aperture restrictions. Regarding industrial radar level gauging, the maximum antenna dimensions are strictly limited due to standardized nozzle and flange diameters and thus compact directional antennas with low side lobe levels are needed allowing broadband radar operation and simultaneously suppressing signal distortions by unwanted scatterers. By utilizing a prototype setup of the proposed antenna, the anticipated performance gain is proved by measurement results validating the simulated characteristic antenna parameters as well as the improved radar distance measurement accuracy.