Simulating Aperture Coupling of OAM Waves Through an Infinite PEC Plane Using EFIE-MoM-Part I: Validation and Numerical Accuracy

In this first part of our contribution on orbital angular momentum (OAM) wave aperture coupling, an algorithm is implemented and validated. This algorithm simulates aperture coupling through an infinite perfect electrically conducting (PEC) plane using an electric field integral equation (EFIE) based method of moments (MoM) tool at 100 MHz. The aim is to better understand crosstalk introduced within OAM mode systems and the ability of OAM modes to penetrate apertures and interfere with systems behind them. This will be investigated in Part II. Simulating OAM waves accurately is challenging because it involves evaluating small modal differences in complex field amplitudes excited by ports. A surface-based MoM solver is well-suited for this application because it requires only a small discretization effort that can be carefully controlled for accuracy and symmetry. The simulation of apertures in an infinite PEC plane requires simulating either the PEC plane, i.e., an infinite object, or, using Babinet's principle, a finite perfectly magnetic conducting (PMC) plane, which is usually easier. Volume-based finite element method (FEM) solver can approximate PMC structures but face accuracy challenges and volume limitations. The presented algorithm exploits the similarities in the scattering of PMC and PEC surfaces in an MoM solver to emulate a simulation of PMC surfaces.