A Generalized Synthesis Technique for High-Order Bandpass Frequency-Selective Surfaces via Rectangular Patch Resonators and Coupled Apertures

In this paper, an accurate and generalized synthesis technique for a class of high-order bandpass multi-layer frequency-selective surfaces (FSS) is proposed. The proposed FSS consists of alternately stacked rectangular patch resonators and coupling apertures. Firstly, the rectangular patch resonator can be regarded as a transversal stripline resonator, and the coupling aperture can be equivalently modeled as an impedance transformer cascading two inductors. Secondly, using the numerical short-open-load (SOL) calibration technique, the equivalent electrical parameters of the proposed FSS can be accurately extracted. By quantitatively mapping the equivalent circuit model (ECM) to a Chebyshev bandpass filter network, the synthesis technique can be realized. Finally, to verify the correctness of the proposed method, a third-order bandpass FSS is synthesized with the theoretical predictions aligning well with the simulated results.