Wideband resonate cavity antenna with double‐layer metallic superstrate.

Resonate cavity antennas (RCAs) with metallic superstrate, whose slot structure leads to an intense inductive property, resulting in high reflection coefficients, typically have a narrow bandwidth. This study explores designing wideband RCAs using a double‐layer metallic superstrate. Two metallic layers with an air gap that can be considered a cascade capacitance, are expected to significantly reduce the metallic superstrate's inductive property and thereby the reflection coefficient. As a sample, an RCA using a double‐layer metallic superstrate working at 10 GHz and with a size of 3 λ0 × 3 λ0, where λ0 is the wavelength corresponding to the working frequency, is designed, fabricated and measured. Results show that the proposed RCA achieves a wide bandwidth up to 18.25% (from 9.51 to 11.42 GHz) and gets a gain of 17.31 dBi at the working frequency of 10 GHz. [ABSTRACT FROM AUTHOR]