An Effective Via-Based Frequency Adjustment and Minimization Methodology for Single-Layered Frequency-Selective Surfaces

This paper proposes a new methodology for minimizing the size of the periodic element and tuning the resonant frequency of a single-layered frequency-selective surface (FSS). Vertical vias are introduced to the FSS design in the methodology. This via-based methodology can be applied to nearly all of the single-layered FSSs presented in the literature, which exhibit much more convenience in practice than the multilayered FSSs. Through the proposed methodology, users can easily vary the resonant frequency of the considered via-inserted FSS (VI-FSS), adding only some additional vias and without having to modify the original element pattern. In addition, the proposed methodology can be applied to minimize the element size or lower its resonant frequency. To illustrate the methodology, the well-known Jerusalem Cross (JC) FSS was first considered. A high-order equivalent circuit was suggested to model the physical mechanism of the VI-FSS with the applied methodology. A set of closed-form equations was also provided to calculate efficiently the circuit inductances and capacitances, especially those caused by the added vias. The VI-FSS prototype was fabricated and examined in a fully anechoic chamber. Favorable agreement among the proposed circuit, full-wave simulation, and measurement was achieved. For demonstrating the capability of the via-based methodology further, it was applied to two advanced applications: 1) two miniaturized-element FSSs and 2) an FSS absorber. Thus, a significant performance improvement in these applications reconfirmed the capability of the proposed methodology.