Investigation Into the Effects of the Reflection Phase Characteristics of Highly-Reflective Superstrates on Resonant Cavity Antennas

First we describe two frequency selective surfaces (FSSs), one capacitive and the other inductive, that are designed to exhibit identical high-reflection magnitude at an arbitrary frequency. These two FSSs are then employed as the superstrate of two RCAs having identical microstrip patch source. In order to determine the resonant conditions and obtain approximate values for the antenna directivity, RCAs are initially analyzed using the well known simple ray-tracing method. Next, a full-wave analyzer (ANSOFT Designer v4.0), based on the method of moments (MoM), is utilized to thoroughly analyze the RCAs. Experimental results are provided to support the full-wave simulations, as well. In contrast to the prediction of the ray-tracing modeling, which is merely based on the reflection magnitude of the FSSs, it is pointed out that their phase properties have noticeable effects on the RCA gain. Second, two other RCAs are designed based on high permittivity and high permeability superstrates with identical contrast. There, too, it is shown that the reflection phases of the RCA superstrates determine the air-gap heights which in turn affect the RCA gains.