Transmission Zero Controlled Wideband Bandpass FSS

In this paper, a method to interpret the transmission zero frequencies (fzs) in the stopband of a bandpass frequency selective surfaces (FSS) is presented. It is established that f(z)s depends on the surface current distribution on the FSS screen and is governed by the length of the FSS element on which the current density is stronger. Using this method, four f(z)s in the stopband of a novel FSS has been calculated which are: 5.90 GHz, 6.81 GHz, 12.95 GHz, and 14.42 GHz. Out of these f(z)s, the first two f(z)s reside below the -3dB cut-off frequency of the transmission bandwidth. And another two f(z)s resides above the 3dB cut-off frequency. Thus these f(z)s define a wide passband of the FSS which extends from 7.69 GHz to 12.16 GHz with a fractional bandwidth (FBW) of 45.16% The position of f(z)s and the wide bandwidth of the FSS have been experimentally verified.