Wide stop-band cascaded frequency selective surfaces with Koch fractal elements

Numerical and experimental investigations are presented for a cascaded frequency selective surface (FSS) with Koch fractal conducting patch elements. The work is developed in two steps. In the first step two Koch fractal FSS screens are designed using the Ansoft Designer™ software. In the second step these FSS are cascaded and separated by an air gap layer to improve the bandwidth behavior. The structures are cascaded using Teflon spacers and screws to obtain the air gap. Thereafter, a numerical cascading technique is used to analyze the effect of the air gap between the cascading structures.