Spoof surface plasmon-based bandpass filter with extremely wide upper stopband

Liu Xiaoyong^{1, 2}, Zhu Lei^{2, †,}, Feng Yijun^{1, ‡,}

(a) Schematic diagram of the proposed bandpass filter structure. The front (b) and the back (c) side photographs of the fabricated prototype filter. (d) The simulated and measured S parameters of the filter.