MoM analysis of a reflector antenna design for omnidirectional coverage

Radio base stations for point-to-multipoint communications usually employ arrays of antennas at a certain height from the ground for omnidirectional coverage, with element excitations being exercised in order to achieve a suitable elevation pattern synthesis. Prospective reflector designs, while producing cosecant squared-like power patterns in the vertical plane to account for free space attenuation, should also concentrate radiated energy bellow the horizon line for reduced interference. A compact configuration employing a single circularly symmetrical shaped reflector surface fed by an axial horn, has been investigated by Bergmann, Hasselmann and Branco (see Microwave Opt. Technol. Lett., vol.24, p.426-29, March 2000). A specific design of the latter configuration is further explored herein with a view towards evidencing the benefit of a strictly numerical analysis tool such as the method of moments (MoM) for both reflector and feed structures, as compared to the more conventional optical (geometrical and physical) route.