A Wideband, Dual-Polarized, Resonant Cavity Antenna Using Miniaturized-Element Frequency-Selective Surfaces

Resonant cavity antennas (RCAs) provide moderate to high gains (15–20 dBi) with thin profiles, operating at the cavity’s fundamental mode. A recent RCA design employs a spherically modified ground (SMG) to excite higher-order cavity modes with high gain characteristics. However, this design has a large cavity height, and the SMG’s curved surface is costly to manufacture. This article addresses these challenges by introducing a miniaturized-element frequency-selective surface (MEFSS) within the cavity, which replicates the SMG’s performance through polarization-independent time delays on its aperture. Our proposed RCA simplifies fabrication and reduces cavity height by 35%. We validate our approach with simulations and measurements for dual-linear polarization, achieving a 3-dB gain bandwidth of approximately 22% (from 12 to 15 GHz) and a peak gain of 17.5 dBi. Thus, the proposed RCA exhibits high gain, reduced height, and simple configuration, paving the way for advanced applications in microwave and mm-wave frequencies.