A new closed form expression is introduced to estimate the 3 dB pattern bandwidth of a Fabry-Pérot cavity antenna covered by a thin frequency selective surface (FSS) radiating at the broadside direction. The new formula has been obtained by using reciprocity, transmission line theory, and the susceptance model of the FSS. This formula estimates the 3 dB pattern bandwidth more accurately than previous expressions. © 2011 IEEE.

In this paper, an analytical method is proposed to estimate the 3dB power bandwidth of a Fabry-Pérot Cavity antenna covered by a thin frequency selective surface. The 3dB power bandwidth of the antenna is found using the broadside radiation power density of the antenna calculated based on the reciprocity theorem along with a transmission line model of the antenna and the circuit model of the FSS layer. The accuracy of the proposed method is verified by numerical simulations. © 2011 IEEE.