Design of single-layer bandstop fractal frequency selective surface based on WLAN applications

In this letter, we present a new frequency selective surface (FSS) for shielding 2.4-2.5 and 4.98-5.825 GHz wireless local area network (WLAN) bands. This FSS structure is based on the traditional Sierpinski octagon and we improve it. Compared with the traditional structure, the improved one has a smaller element size and better angular stability. The design is realized on float glass with a relative permittivity (& epsilon;r ${\varepsilon }_{r}$) of 8, and the unit cell size is 0.1152 & lambda;0 x 0.1152 & lambda;0 (& lambda;0 is the free space wavelength at the first resonant frequency). Wide rejection bandwidths (-10 dB) of 910 and 1630 MHz are obtained at 2.4-2.5 and 4.98-5.825 GHz, respectively. The surface current distribution and the equivalent circuit model are illustrated to explain the resonance behavior of the proposed FSS. Furthermore, this FSS exhibits stable frequency response to incident angles of 0 & DEG;-80 & DEG; under transverse electric and transverse magnetic polarizations. Finally, this FSS structure was fabricated and measured. The measured results demonstrate that this FSS structure has good performance in WLAN applications.