A Compact Singly Fed Dielectric Resonator Antenna With Flat-Top Radiation Patterns

Flat-top radiation patterns are desired in various scenarios to reduce signal interference from nearby coverage sections. Numerous flat-topped antennas have been proposed, but the existing ones usually have complex feeding networks, bulky sizes, or high profiles. To solve these problems, a compact singly-fed flat-topped dielectric resonator antenna (DRA) is proposed in this article. Based on the principle of pattern superposition, the lower order DRA mode (TE
$^{\text {y}}_{311}$
mode) and the fundamental slot mode are excited simultaneously to obtain flat-top patterns in both the E- and H-planes. To the best of the authors’ knowledge, it is the first time that lower order DRA modes can be utilized to achieve flat-top radiation patterns. Two higher permittivity dielectric slabs are attached to the DRA to move these two modes together, and a metallic wall is added to reduce SLLs. For verification, a prototype operating at 5.8 GHz is designed, fabricated, and measured. The measured radiation patterns are flat-topped in both the E- and H-planes with flat-top beamwidths of 50° and SLLs lower than −17 dB. The flat-top patterns can be maintained from 5.74 to 5.86 GHz with an average gain of 8.2 dBi. Compared with other flat-topped antennas, the proposed antenna has the advantages of a simple structure, compact size, and low profile.