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.

This study aims to present a thin and broadband meta‐surface for both mono‐static and bi‐static radar cross‐section (RCS) reduction being able to operate in large range of incident angles and different polarisations. Meta‐surfaces are formed through the combination of two artificial magnetic conductor (AMC) cells arranged in periodic and randomised fashions in order to suppress the scattered fields in low levels in all directions as well as minimising the maximum RCS of the metallic surface. By appropriate design of each AMC, and using equivalent circuit method, the reflection coefficients of these surfaces are designed in a way to reach 180 (±37°) phase difference over a wide range of frequencies and incident angles. The bandwidth for 10 dB mono‐static RCS reduction is about 53% for both periodic and randomised structures at the normal incidence. It is illustrated that the randomised arrangement structure has 3 dB lower maximum bi‐static RCS compared with the periodic structure. Finally, the periodic and randomised arrangement prototypes are fabricated and measurements of their mono‐static RCS are conducted. The validity of the study design is fulfilled by achieving an acceptable agreement between the measured and simulated results.

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