Analysis and design of frequency selective surfaces using teragon patch elements for WLAN applications

This paper describes a fractal design methodology for frequency selective surfaces (FSSs) composed of teragon metallic patches on a single-layer fiberglass dielectric. Shapes presented by teragons are exploited to design compact FSSs acting as dual-band band-stop spatial filters. An FSS parametric analysis is performed in terms of the fractal dimension and unit cell size of fractal patches. The transmission properties of the proposed periodic arrays are initially investigated through simulations performed by Ansoft Designer (TM) commercial software. To validate the used methodology, three FSS prototypes are selected for fabrication, and one of them is designed to reject wireless local area network signals in the bands of 2.4-2.5 GHz (IEEE 802.11b) and 5.0-6.0 GHz (IEEE 802.11a). Experimental characterization of the FSS prototypes is accomplished through an alternative setup with elliptical monopole microstrip antennas for low-cost FSS measurements. The obtained results point to interesting features for FSS spatial filters: compactness, with high values of frequency compression factor (up to 80.4%); dual polarization; dual-band frequency responses; and stable resonance frequencies at oblique incidence.