Leveraging Symmetry in the Analysis of Mirror-Symmetric Multilayered Periodic Structures With Application to LP-to-CP Converter Design

This communication proves that the analysis of the scattering by a mirror-symmetric multilayered periodic structure (MPS) can be replaced by the analysis of the scattering by two semi-structures with half the size in which the symmetry plane behaves either as a perfect magnetic conductor (PMC) or as a perfect electric conductor (PEC). The proof is based on the reflection properties of the electric and magnetic fields through PMCs and PECs, and it is valid for arbitrary oblique incidence. As an application of this concept, the spectral-domain method of moments (SD-MoM) is reformulated to deal with MPSs limited by PMCs and PECs, and it is used in the design of a mirror-symmetric multilayered linear polarization (LP)-to-circular polarization (CP) converter. The results obtained with SD-MoM are validated by comparison with commercial software CST. Numerical simulations show that the CPU time required by both SD-MoM and CST in the analysis of half the LP-to-CP converter limited by PMC and PEC is between 30% and 42% smaller than that required by the analysis of the complete LP-to-CP converter, which shows the numerical advantage gained in exploiting the symmetry when it is present.