Circuit Model Analysis of Switchable Perfect Absorption/Reflection in an Active Frequency Selective Surface

This paper presents a switchable perfect absorber/reflector in S band using a PIN diode integrated active frequency selective surface (AFSS). It is numerically demonstrated that the AFSS shows over 99% absorptivity at 3.5 GHz when the diode is forward biased, whiles reflects over 99% incident power when the diode is inversed biased. An equivalent circuit (EC) model is further developed to characterize the AFSS's switchable electromagnetic performance and aim at model optimization. The empirical formulas and curve fitting technology have been employed to get the lumped element parameters in the EC model. Special considerations are given to physical attributes, including the dielectric permittivity and thickness of the substrate. The consistency of the electromagnetic simulations and EC analysis demonstrates the high accuracy of the developed EC model.