Equivalent circuit model for array of circular loop FSS structures at oblique angles of incidence

This study aims to introduce a simple equivalent circuit model of circular loop shaped frequency selective surface (FSS), predicting the plane‐wave transmission characteristics for oblique angles of incidence. The equivalent circuit model is based on a series of basic equations in order to calculate the inductance and capacitance of strip gratings. Through provided relations, the values of circuit elements can be calculated as well. The proposed relations are applied to many circular loop FSSs with different dimensions, and the results are compared with the full‐wave simulations obtained from computer simulation technology microwave studio. Moreover, some comparison graphs between the simulated and analytical resonant frequency for different values of design parameters have been carried out to show the circuit model follows the trend of the simulated responses. Finally, both the FSS structures have been fabricated and measured in an anechoic chamber. A good agreement between the experimental results and the simulated responses demonstrates the validity of the circuit model.