An alternative technique in designing a low-profile two-pole bandpass Frequency Selective Surface (FSS) using aperture coupling interlayer

This paper presents an alternative design approach for low-profile, two-pole bandpass Frequency Selective Surface (FSS) using an aperture-coupling interlayer. In addition to this proposed method in providing close spacing between the FSS resonator layer, miniaturized complementary Jerusalem cross shaped FSS is used to further maintain a robust filtering response to oblique-angled plane waves. The proposed technique is not limited to a particular FSS shape and can be applied for arbitrary separation between the FSS layers. To demonstrate the proposed method, a two-pole FSS with the unit-element dimension of much less than λ_o/2 and total thickness of around λ_o/30 is designed using the aperture interlayer and measured. Both simulated and measured results show selective two-pole filtering response that is robust for various oblique angle incidences and polarizations.