A Novel 2.5-Dimensional Ultraminiaturized-Element Frequency Selective Surface

This paper proposes fabricating a new 2.5-dimensional ultraminiaturized element on a cost-effective printed circuit board to build a frequency selective surface (FSS). The proposed element consists of two main parts: a planar tapered meandering line (PTML) and a vertical via-based meandering line (VVML). Compared with previous published two-dimensional miniaturized elements, the proposed element is smaller (only 3.3% of the free space wavelength at the resonant frequency) and exhibits high resonant stability at various polarizations and incidence angles (only 0.4% deviation at the resonant frequency when the incident angle is as great as 75°). In particular, the introduction of VVML in the element substantially improves the FSS performance. A third-order equivalent circuit model was established to model the FSS performance precisely. This model can be reduced to a simpler first-order model, thus enabling the resonant frequency of the FSS to be predicted quickly. A prototype of the ultraminiaturized-element FSS was created and examined. The results of the proposed models, full-wave simulation, and measurement exhibited satisfactory consistency.