Method for Electromagnetic Property Extraction of Sublayers in Metal-Backed Inhomogeneous Metamaterials

Abstract

A scattering (S-) parameter method has been proposed for electromagnetic property extraction of a target layer within metal-backed inhomogeneous metamaterial (MM) structures. It relies on recursive S-parameters for two different polarizations (parallel and perpendicular). Two different algorithms depending on the value of the incidence angles were proposed to add flexibility to our method. The algorithms were first validated by a metal-backed quasi-one-port method applicable only for one-layer (homogeneous) samples. Then, they were applied to extract electromagnetic properties of the split-ringresonator-wire MM slab of a metal-backed two-layer inhomogeneous structure and the Omega MM slab of a metal-backed four-layer inhomogeneous structure, and extracted properties by our algorithms were compared with those retrieved by different methods applicable for homogeneous samples only. The accuracy of our method was also examined when there was some noise in S-parameters, when there was a misalignment in incidence angles, and a when large value of iteration number was used. INDEX TERMS Metamaterials, inhomogeneous, recursive algorithm, retrieval, constitutive parameters, metal-backing.

Robust Effective‐Medium Characteristics of Bianisotropic Reflective Metasurfaces based on Field‐Circuit Combined Analysis

“…The retrieval results of the annular-slot mode in the y-direction match the ones of the isotropic annular-slot unit cell using a previous theory. [31] This not only directly demonstrates the effectiveness of the results of the y-direction, but also indirectly validates that the theory can be employed to calculate the effective EM parameters in the x-direction. Therefore, the effective-parameters theory for bianisotropic metasurfaces in this work is reliable and valid.…”

“…In this case, the retrieval methods of homogenous and isotropic metamaterials or metasurfaces can be applied to calculate the CEPs. Therefore, the retrieval method for single‐layer metal‐backed metamaterials (homogenous and symmetric) in a previous study [ 31 ] is used to calculate the CEPs as a comparison with the proposed theory as shown in Figure 7. Particularly, the target unit cell of the previous method is an annular‐slot element as shown in Figure a with the same sizes as the proposed cell.…”

“…Recently, Zhang's team proposed a method [29,30] to extract the effective circuit parameters (capacitance and inductance) using obliquely incident plane waves. Particularly, in this year, a robust method [31] has been proposed to retrieve the CEPs of inhomogenous metalbacked metamaterials. However, as for anisotropic and asymmetric reflective metasurfaces, few valid retrieval theories are proposed.…”

Broadband, Stable, and Noniterative Dielectric Constant Measurement of Low-Loss Dielectric Slabs Using a Frequency-Domain Free-Space Method

“…There are some issues related to free-space techniques. First, these techniques require exact knowledge of the sample thickness prior to material characterization [12], [13], [14], [15], [16], [17]. The free-space techniques in the studies [18], [19], [20] can be used to determine electromagnetic properties of materials without using their thickness information.…”

“…Third, free-space techniques generally use both reflection and transmission scattering (S-)parameter measurements to determine electromagnetic properties of the sample. Nevertheless, transmission measurements are not adequate for electromagnetic characterization of samples whose backs are not accessible [16], [17]. Besides, any misalignment of transmitting and receiving antennas can reduce measurement accuracy for transmission free-space S-parameter measurements.…”