Dual-mode aperture-coupled patch resonator based dual-band higher-order frequency selective surfaces

In this article, a low profile aperture coupled dual band higher order bandpass frequency selective surface (FSS) is proposed. To begin, a simple patch resonator with an L-shaped truncated corner is theoretically examined such that two orthogonal modes can be activated at the same time. Following that, a combination of four identical L -shape truncated patch resonators with 90 rotation between two adjacent patches is developed and analyzed to avoid the reflection of cross -polarized produced by orthogonal modes. Further, by arranging two of such combination resonators placed back-to-back through aperture coupling metallic layer in the middle, a three layer single mode fourth order bandpass FSS is designed. The proposed bandpass FSS is twice the performance of traditional aperture coupled patch resonators (AC-PRs). It provides more flexibility at higher order filtering responses. To endorse the design concept, a dual -band fourth order bandpass FSS is simulated to initiate magnetic and electric coupling through the aperture metallic layer. Moreover, an equivalent circuit model for even and odd mode analysis is examined for the principle of operation. Finally, the proposed bandpass FSS is fabricated and tested in a vector network analyzer (VNA) setup. The measured and simulated results are compared and validated.