Design of an unidirectional UWB cavity backed antenna

This paper presents a low profile unidirectional UWB cavity backed antenna analyzed using The Theory of Characteristics Modes (TCM). The main goal of this work is to design a low profile UWB antenna with a very stable and unidirectional radiation pattern. The proposed design is based on exciting the fundamental mode of a cavity structure composed of a metallic ring, a circular waveguide and two circular feeds. The feeding structure used to excite this mode is symmetric and is implemented with a capacitively-coupled dual-feed circular aperture. In addition, an analysis of the operation of the structure is performed, according to the TCM. The −10 dB bandwidth obtained is 89.71% (3.48 GHz to 9.15 GHz), with unidirectional radiation patterns. An antenna with this bandwidth, as well as unidirectional and stable radiation pattern features can be used in many applications.