Part 1 – Eigenfunction Expansion (EFE) Analysis of Cylindrical
Metasurfaces: Zero ThicknessTensorial Surface Susceptibility Model
Abstract
We present a rigorous semi-analytical formulation for the analysis of
electromagnetic (EM) scattering from a cylinder constructed from a
metasurface represented using surface susceptibilities. The formulation
uses the Generalized Sheet Transition Conditions (GSTCs) to represent
the surface and eigenfunction expansion (EFE) of the incident and
scattered fields, by exploiting their angular periodicity. Incorporating
a completely general non-uniform surface formulation of 36
susceptibility components, a matrix equation is formulated that can be
solved for the field harmonic coefficients. The paper illustrates the
methodology with a number of examples; including two formed from a
finite sized practical unit-cell exhibiting a normally oriented magnetic
resonance which is compared with commercial EM full-wave solver; other
examples present surfaces that have a modulated gain/loss profile (i.e.
amplitude modulation) and polarization conversion. It is found that for
all cases the EFE solution very accurately captures the scattered fields
in both the interior and exterior regions of the surface. Detailed
convergence studies are further presented including the effect of
susceptibility modulation on the number of terms needed in the EFEs, to
reach a correct field solution. The proposed EFE framework is further
compared with a second GSTC based simulator using an Integral Equations
(IE) approach and it is found that the IE-GSTC simulated fields approach
that of the EFE as the surface discretization is increased. The proposed
EFE approach is thus a quick, rigorous methodology which, although
limited in the geometry which it can model, has many advantages for
investigation into the use of GSTCs, application development and
providing a baseline for simulation studies.