Grbic, Anthony

Vecchi, Giuseppe

Verni, F.

English

VERNI', FRANCESCO

Anthony Grbic

Giuseppe Vecchi

PORTO@iris (Publications Open Repository TOrino - Politecnico di Torino)

04 August 2020POLITECNICO DI TORINORepository ISTITUZIONALENumerical Simulation of Cascaded Planar Metasurfaces Exhibiting Bianisotropic Properties / Verni, F.; Grbic, Anthony;Vecchi, Giuseppe. - (2018). ((Intervento presentato al convegno 2018 IEEE International Symposium on Antennas andPropagation and USNC-URSI Radio Science Meeting tenutosi a Boston nel 8 - 13 July 2018.OriginalNumerical Simulation of Cascaded Planar Metasurfaces Exhibiting Bianisotropic PropertiesieeePublisher:PublishedDOI:Terms of use:openAccessPublisher copyrightcopyright 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all otheruses, in any current or future media, including reprinting/republishing this material for advertising or promotionalpurposes, creating .(Article begins on next page)This article is made available under terms and conditions as specified in the  corresponding bibliographic description inthe repositoryAvailability:This version is available at: 11583/2712390 since: 2018-09-06T18:17:24ZIEEENumerical Simulation of Cascaded Planar MetasurfacesExhibiting Bianisotropic PropertiesF. Vern´ı*1, A. Grbic2, and G. Vecchi11 Dipartimento di Elettronica e Telecomunicazioni, Politecnico diTorino, Torino, Italy2 Department of Electrical Engineering and Computer Science,University of Michigan, Ann Arbor, MI, USAMetasurfaces (MTSs) are electrically-thin metamaterial layers designed to exhibit unusualreflective/refractive properties or guided wave characteristics. The goal of this work is todevelop a full-wave fast-solver (Method of Moments based on Fast Fourier Transform) for thedesign of metasurfaces with bianisotropic responses, with a special emphasis on modulatedmetasurfaces, i.e. aperiodic cell arrangements. Bianisotropic metasurfaces can be realizedby cascading multiple isotropic/anisotropic electric sheet admittances (patterned metalliccladdings), with dielectric spacers separating them. Here, we present a numerical, spatialdomain approach to computing the electromagnetic response of cascaded planar electric sheetadmittances by means of Surface Integral Equations (SIEs). Each sheet admittance (i) ismodeled as a zero-thickness electric discontinuity characterized by the following ImpedanceBoundary Condition (IBC):eav = Z ie · jav (1)where Z ie is a 2 × 2 tensor, which can be anisotropic, and varying in space. The terms javand eav represent the electric surface currents and the average electric field tangential to thesurface Σi, respectively. Assuming an arbitrary incident field, einc, we can write the ElectricField Integral Equation (EFIE) for planar cascaded metasurfaces as:nˆ× (Ze · j) + nˆ× Z0L (j) = nˆ× einc (2)where L is the Electric Field Integral Operator (EFIO). A conventional Galerkin testingprocedure is assumed. The overall domain Σ =⋃Σi is approximated by a mesh of planartriangles. The solution j is approximated as j ≈ ∑n jnfn where fn, n = 1, . . . , N are Rao-Wilton-Glisson (RWG) basis functions defined on the N internal edges of the mesh. Theunit vector nˆ is normal to the surface Σ. Ze is a matrix which accounts for the contributionof each impedance tensor Z ie. It should be noted that the tensor Z ie does not include thedielectric spacers. The spatial dispersion resulting from the electrical thickness of the cas-caded metasurface (multiple electric sheet admittances separated by spacers) is taken intoaccount by the Green’s functions for multi-layered media. It is worth noting that cascadedmetasurfaces can also be analytically modeled as a single bianisotropic Generalized SheetTransition Condition (GSTC) with spatially dispersive surface parameters. In the designof bianisotropic metasurfaces, one typically goes from the single bianisotropic GSTC sheetto a realizable, cascaded metasurface consisting of multiple electric sheet admittances. Thisprocess can be performed analytically using Wave Matrices for periodic metasurfaces (A.Ranjbar and A. Grbic, Phys. Rev. B, 95, 205114, 2017), but becomes rather challenging foraperiodic designs. The goal of the proposed full-wave solver is to aid in this process, andavoid approximate strategies such as employing the local periodicity approximation.

Numerical Simulation of Cascaded Planar Metasurfaces Exhibiting Bianisotropic Properties

https://iris.polito.it/retrieve/handle/11583/2712390/207151/ursi2018_final.pdf

Numerical Simulation of Cascaded Planar Metasurfaces Exhibiting Bianisotropic Properties

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