Two-level optimization of a stepped dielectric superstrate to increase gain of a resonant cavity antenna

In this paper, customized full-wave optimization of resonant cavity antennas (RCAs) is presented. The objective was to design RCAs with a high directivity-bandwidth product (DPB) for medium-to-high-gain space-limited applications. For this, a speed-constrained particle-swarm optimization (SMPSO) algorithm was implemented in MATLAB, which iteratively interacted with the 3D full-wave simulator of CST Microwave Studio during the optimization process. The optimization resulted in a stepped dielectric superstrate, which when used in an RCA demonstrated a measured broadside directivity of 20.7 dBi with an extremely large directivity bandwidth of greater than 50%.