A high gain uniplanar end‐fire electrically small antenna with a spilt‐ring resonator loading

Abstract

AbstractThis letter presents a design of a high gain uniplanar end‐fire electrically small antenna. The design starts from an equivalent antenna of an antenna array with two half‐wavelength dipoles, which consists of two linear strips and produces the end‐fire unidirectional radiation. Two U‐shaped strips are utilized to replace the linear strips, which makes the antenna compact. In addition, a spilt‐ring resonator is loaded to make the realized gain of the electrically small antenna increase by ~2 dB. An antenna prototype is fabricated and measured. The measurements reveal that the proposed antenna has a peak realized gain of 6.02 dBi and a front‐to‐back ratio of 12.71 dB at its resonance frequency of 747.8 MHz. Its size is only 0.254 λ0 × 0.184 λ0 × 0.0037 λ0, and ka = 0.984. The measured realized gain exceeds both the Harrington and Kildal–Best ka‐based upper limits.