Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Simple Equivalent Circuit Approach for Anisotropic Frequency Selective
  Surfaces and Metasurfaces   An equivalent circuit model for Frequency Selective Surfaces (FSS) comprising
anisotropic elements is presented. The periodic surface is initially simulated
with an arbitrary azimuthal incidence angle and its surface impedance matrix is
derived. The impedance matrix is subsequently rotated by an angle
$\varphi^{rot}$ on the crystal axes $\chi_1$, $\chi_2$ thus nullifying its
extra diagonal terms. The rotation angle $\varphi^{rot}$ is derived according
to the spectral theorem by using the terms of the matrix initially extracted.
The diagonal terms of the rotated matrix, that is, the impedances $Z_{\chi_1}$
and $Z_{\chi_2}$, are finally matched with simple LC networks. The circuit
model representation of the anisotropic element can be used to analyse
anisotropic FSSs rotated by a generic azimuth angle. The methodology provides a
compact description of generic FSS elements with only five parameters: the
lumped parameters of the LC network $L_{\chi_1}$, $C_{\chi_1}$, $L_{\chi_2}$,
$C_{\chi_2}$ and the rotation angle $\varphi^{rot}$. The circuit model can take
into account the presence of dielectric substrates close to the FSS or a
variation of the FSS periodicity without additional computational efforts. The
equivalent circuit model is finally applied to the design of two transmitting
polarization converts based on anisotropic metasurfaces.

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The categories of this paper are: cond-mat
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The categories of this paper are: q-alg
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The categories of this paper are: hep-lat
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The categories of this paper are: q-bio
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The categories of this paper are: plasm-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: econ
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The categories of this paper are: stat
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The categories of this paper are: cs
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The categories of this paper are: nucl-ex
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The categories of this paper are: dg-ga
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The categories of this paper are: mtrl-th
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The categories of this paper are: math-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-th
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The categories of this paper are: quant-ph