A non-uniform design of the metamaterial superstrate for the resonant cavity antenna with wideband property

As a high gain antenna with strong resonant property, the resonant cavity antenna (RCA) is confronted with a narrow bandwidth. To tackle this problem, this paper proposes a novel method of designing a non-uniform metamaterial-inspired superstrate for the RCA. To enhance its bandwidth, unit cells on the proposed superstrate varies their dimension with respective to their distance to the superstrate's center according to an exponent function. A RCA working at 10 GHz and covered with such a non-uniform metamaterial superstrate is designed, fabricated and measured. Results show the proposed nonuniform metamaterial superstrate improves the RCA's |S11|<−10 dB impedance bandwidth from 0.36% to 3.11%, and meanwhile keeps almost the same gain, side-lobe level and cross polarization level for the RCA.