Equivalent Circuit Model for Metamaterial-Based Electromagnetic Band-Gap Isolator

This letter describes the performance characteristics of single-layer 1-D periodic resonant structures embedded in a metal-backed substrate. Such structures are known to behave as an electromagnetic band-gap (EBG) layer that can suppress the dominant substrate mode. For short distances in thin substrates, it is shown that the dominant TM₀^odd with a zero cutoff frequency can be approximated by a TEM wave inside and in the vicinity of the thin substrate. The propagation of this TEM wave is then modeled by an equivalent transmission-line model. The effect of the resonant EBG structure on the wave propagation in the equivalent transmission-line model is taken into consideration by modeling the EBG structure in terms of an equivalent LC circuit and establishing the proper electric and magnetic mutual couplings between the LC circuit and the transmission-line model. The performance of the equivalent circuit model is compared to the full-wave simulation of the actual structure, and a very good agreement is shown.