Comparison of Capacitive and Inductive Partially Reflective Surface Antenna Using Ray-tracing

A partially reflective surface (PRS) antenna is a low-cost high gain antenna, which is often classified by the capacitive or inductive nature of the PRS. It has been shown that, for a given reflection magnitude, capacitive PRS facilitates a larger antenna gain than inductive PRS, based on leaky-wave model and practical design examples. In this paper, we extend the classical ray-tracing approach to derive analytically that the superior gain is primarily due to the greater height of the capacitive PRS from the ground plane, which leads to a smaller phase delay and a more uniform magnitude distribution across the PRS. To verify the analytical study, the simulated phase and magnitude distributions of a capacitive and an inductive PRS antenna were produced and shown to agree with the predicted trends of the phase and magnitudes distributions from ray-tracing. The gain of the antenna with the capacitive PRS is 16.6 dBi, which is 1.8 dBi higher than that of the antenna with the inductive PRS. This insight on the effect of PRS height on phase delay gives more clarity to the operating principle of PRS antenna.