Design of a single-layer compact multi-band frequency selective surface exhibiting angular and polarization stability for WLAN applications

This study proposes a compact frequency selective surface (FSS) for the application of the WLAN frequency band․ The designed FSS works for 2․4 GHz‚ 3․65 GHz and 5․0 GHz․ The unit cell size for the miniaturized patch is 7․4 mm × 7․4 mm × 1․6 mm․ An FR-4 substrate is used with thickness 1․6 mm and strip width of 0․3 mm․ The combination of convoluted meander line with the square spiral version is the result of the miniaturization and dual-band‚ tri-band performances․ The design is evaluated in full-wave simulations in CST Microwave Studio․ The FSS exhibits stable transmission characteristics with distinct resonances in the pass bands‚ with frequency selectivity values of approximately −14‚ −23 and − 20 dB at 2․4‚ 3․65 and 5 GHz‚ respectively‚ and angular characteristics spanning up to 90° in both TE and TM modes․ The design is polarization insensitive over the full 0°-90° scan range. A manufactured prototype by 300 mm × 300 mm was used for experimental validation. The suggested FSS’s dependability is demonstrated by a strong correlation between the simulated and measured responses, with the discrepancy in resonant frequencies being 1%․ For instance‚ the proposed FSS shows a high degree of miniaturization‚ with an electrical dimension of less than 0․06λ at 2․4 GHz‚ while keeping a good performance․