A novel ultra-wideband pattern diversity antenna for high-gain applications

An ultra-wideband (UWB) pattern diversity antenna design is proposed for high-gain applications and simulation and measurement results are presented. The proposed antenna is compact in size (50×41×21 mm³) and easy to fabricate. Its structure consists of two parallel disk radiating elements, each fed at two points by two microstrip lines. Ground plane is shaped like a cavity with two edges at an angle 70°. The disks are also slightly modified in geometry to suppress unwanted radiation and increase port isolation. The radiation pattern of the antenna is either directional or squinted for out-of-phase and in-phase excitations, respectively, which resembles the sum and difference patterns in monopulse feeds. Simulation results show -10 dB impedance bandwidths extending from 5 to more than 15 GHz. The radiation patterns maintain less than -15 dB sidelobe, backlobe and cross-polarization levels from 5 GHz up to 9 GHz. The pattern measurements are carried out on a prototype antenna for 6.5-8.5 GHz and show good agreement with the simulation data. The measured gain of the sum pattern in this band, varies from 8.6 dBi to 11.2 dBi, with less than -15 dB sidelobe, and cross-polarization levels. The peak gain of difference mode varies between 3 dBi to 5.5 dBi. This antenna can be used as a standalone directive wideband antenna, as a reflector feed, or for monopulse tracking applications.