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

Abstract

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 TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">odd</sup> 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 <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> circuit and establishing the proper electric and magnetic mutual couplings between the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> 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.