Wideband High-Gain Open Resonator Antenna Using a Spherically Modified, Second-Order Cavity

In this communication, we present a simple yet unconventional wideband resonant cavity antenna (RCA) with high gain and large gain-bandwidth product (GBP). The bandwidth enhancement of the RCA is approached by using a second-order height resonant cavity comprising a dielectric slab of high permittivity as the partially reflective surface and a ground plane with spherically modified geometry. It is shown that by imitating an open resonator structure, the spherically modified cavity can support multiple quasi-Laguerre-Gaussian beam modes and hence, dramatically improve the operation bandwidth of the RCA. A RCA with large GBP is designed, simulated, and then verified through measurement. Measured results show a bandwidth of 25% with a peak gain of 17.7 dBi. The proposed low-cost and easy-fabricate method shows its effectiveness in increasing the bandwidth for the RCA.