Frequency-selective electromagnetic transmission through dielectric-filled double rectangular apertures in parallel PEC plates using the method of auxiliary sources

This study presents the electromagnetic wave transmission characteristics of a double rectangular aperture structure formed by two parallel perfectly electrically conducting (PEC) plates separated by a dielectric medium, illuminated by arbitrarily polarized waves incident from a Hertzian dipole source. Using the Method of Auxiliary Sources (MAS), a numerically efficient and singularity-free approach, the research investigates the effects of aperture size, dielectric constant, and separation distance on the frequency-selective transmission behavior of the structure. The results reveal that the structure exhibits tunable high-pass filtering structure behavior, with both cutoff frequency and transmitted power strongly dependent on geometric and dielectric material parameters. Larger apertures and higher permittivity values enhance transmission efficiency and shift the cutoff frequency to lower values. Field distribution analyses further illustrate the effects of geometric and dielectric material configurations on field penetration and coupling strength. The MAS results show good match with full-wave FEKO simulation while offering significant computational advantages. These findings provide a flexible and scalable framework for designing tunable filters, antennas, shielding devices, and waveguide structures across a wide range of electromagnetic applications.