Dual-Polarization Multibandstop 3-D Frequency-Selective Structures Based on Cross-Coupling Method and Subcell–Cell Structure

Abstract

In this article, based on cross-coupling way and subcell–cell structure, a methodology to design the low-profile dual-polarization multibandstop 3-D frequency-selective structure (FSS) is proposed. Using the 3-D periodic vertical placing printed circuit board pieces (PVPCB) structure, a first-order multibandstop FSS is proposed and analyzed first. For this first-order multibandstop FSS, the number of working stopbands is determined by the number of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$LC$ </tex-math></inline-formula> resonators in the edge of PVPCB structure. Then, this first-order multibandstop FSS is used as the basic resonator and crossly placed in the substrate of the PVPCB. This cross placement achieves the coupling between the basic resonators, and a single-polarization second-order bandstop FSS is obtained. Subsequently, this single-polarization second-order multibandstop FSS is used as the subcell, and a novel placement of this subcell ensures that the proposed second-order bandstop FSS can operate in dual-polarization with cross-polarizations of ≤−15 dB. In the whole modeling process, the equivalent circuit model is established to explain the working principle. Finally, to verify the proposed methodology, two examples with two and three working stopbands are designed, fabricated, and measured. The measured results show that the proposed dual-polarization FSS has stable filtering performance under different polarizations and oblique incident angle up to 30°.