A Synthesis Technique for Compact High-Order Bandpass Frequency-Selective Surfaces via Alternately Stacked Patch Resonators and Coupled Apertures

Abstract

An accurate synthesis technique based on planar multilayer manipulation for a class of compact high-order bandpass frequency-selective surfaces (FSSs) is proposed in this communication. The proposed FSS consists of alternately stacked shielded patch resonators and coupled narrow apertures. Here, each coupled narrow aperture is modeled as an equivalent K-inverter, and each shielded patch resonator is considered as an equivalent series stripline resonator. In analysis, the numerical short-open-load (SOL) calibration technique is employed to de-embed the shielded patch resonator, enabling accurate acquisition of a complete equivalent circuit model (ECM) and extraction of all equivalent electrical parameters. Additionally, by quantitatively mapping the ECM of the proposed FSS to an nth-order bandpass filter network, a relevant synthesis technique is proposed. To validate the proposed method, a third-order bandpass FSS is synthesized, and the simulated results align well with the theoretical predictions. Finally, the circuit is modified into a dual-polarized FSS, fabricated, and tested, with measured results closely matching the simulated results. Compared to the prior synthesis techniques for multilayer FSS and 3-D FSS, the proposed synthesis technique demonstrates a high level of consistency between simulated results and theoretical predictions, in addition to size compactness.