Accurate Equivalent-Circuit Descriptions of Thin Glide-Symmetric Corrugated Metasurfaces

Abstract

Thin artificial surfaces that act as high frequency band-gap structures have been recently studied for the design of gap waveguides, hard surfaces, and planar lenses. Here, we propose a circuit-based method to analyse glide-symmetric corrugated metasurfaces that are embedded in a thin parallel plate waveguide. Our closed-form solution is based on rigorous analytical derivations. It achieves remarkable agreement with full-wave solvers, even when the waveguide thickness is extremely thin. In contrast, classical homogenization approaches are shown to be inaccurate for thin waveguides due to the interaction of higher-order Floquet modes between the surfaces. Numerical results validate our theoretical analysis and show the utility of the proposed method.

Glide-Symmetric All-Metal Holey Metasurfaces for Low-Dispersive Artificial Materials: Modeling and Properties

“…2(a), can be described with a homogenized impedance [38], [39], this model does not hold in the presence of two strongly interacting surfaces as in a glide-symmetric configuration. The problem was recently addressed in [40] by means of an equivalent circuit, where an interpretation of the effect of the glide-symmetry is given in term of an effective division by half of the period. Furthermore, the structures of interest for graded-index lenses applications, as in [14], are characterized by a very large ratio size of the hole vs. gap between surfaces.…”

Dissipation Losses in Artificial Dielectric Layers

“…where Y TE and Y TM are no longer pure susceptances as in the lossless case, but they are given by Equations (10), (11) and (12) are also valid for the lossless case, by simply imposing Z s = 0. Figure 4 shows the circuit representation of the equivalent layer impedance.…”

“…7(b) can be used, where the admittances of the layers are separated into infinite-cascade and semi-infinite-cascade solutions, to describe the middle layers and the layers at the edges, respectively. To account for the reactive coupling between layers, the admittances terms in (11) and (12) are now generalized as follows:…”

“…Although Fig. 1(b) depicts the case of maximum shift (layers are shifted by half of the period), the shift can be an arbitrary percentage of the unit cell size, realizing an example of glide symmetric structure [11]. It was shown in [10] that the shift greatly increases the effective refractive index of the ADLs with respect to the aligned case, thus it constitutes a key parameter for more flexible designs.…”

Propagation characteristics of periodic structures possessing twist and polar glide symmetries

“…This stop-band can be used to design low-cost gap waveguides [22][23][24] and low-cost contact-less waveguide flanges for millimeter wave measurements [25]. Due to the beneficial properties of glide symmetry, several methods for fast calculation of the dispersion characteristics of glidesymmetric structures (Cartesian and polar) have been presented [8,[26][27][28]. In these methods, by using the generalized Floquet theorem [4], the computational time is reduced and a valuable physical insight to the phenomenon of glide symmetry is provided [27].…”