Bandwidth and Gain Enhancement of Ridge Gap Waveguide H-Plane Horn Antennas Using Outer Transitions

In this communication, solutions are developed for gain and bandwidth enhancement of a ridge gap waveguide (RGW) H-plane horn antenna. Intrinsic features of RGW allow us to introduce a simple transition at the antenna aperture making its impedance matching with outer space easier, leading to antenna bandwidth enhancement. Two transitions, stepped and tapered, are introduced. The proposed transitions are fully designed as a part of horn flared part and do not introduce any expansion to the antenna length, contributing to its compactness. Furthermore, the modified form of the proposed RGW H-plane horn in which the antenna aperture is squinted is also presented. In this form, the backward radiation is reduced leading to 2 dB gain enhancement.