Design of a feed horn for a FWA base station antenna through FDTD method

A base station antenna for the fixed wireless access system (FWA) is designed. The antenna is composed of a reflector and a feed horn. As for a feed horn, a TM₀₁ mode horn is employed in order to achieve an omnidirectional coverage in the horizontal plane. The curvature of the reflector is shaped so as to achieve a cosecant squared beam in the vertical plane. In this paper, low sidelobe radiation patterns are achieved by inserting a shaped dielectric lens in the feed horn. Through analyzing electrical field distributions on the horn aperture by a FDTD simulator, the optimum lens shape is designed. Electrical field distributions inside and outside the lens horn are calculated. Radiation patterns are also calculated. Through calculated results, effectiveness of a shaped lens and low sidelobe characteristics are ensured.