Capacitively Coupled Spoof Surface Plasmon Unit Cells Based Transmission Line with Band Rejection Capability

In this paper, a method to achieve band rejection within the operating band of the spoof surface plasmon polariton (SSPP) transmission line is reported. Capacitive coupled unit cells are incorporated at a definite interval in the realization of the spoof surface plasmon polariton transmission line. The surface matching of spoof surface plasmon line is disturbed at some frequencies by introducing the capacitively coupled unit cells which creates a rejection band. The proposed structure exhibits a rejection band in the frequency range 8.7-9.9 GHz while maintaining the low pass characteristic of the SSPP line at other frequencies up to cut-off frequency of the line. The measured transmission coefficient is less than -20 dB over the rejection band, which proves that the signal having frequencies in the range 8.7-9.8 GHz gets rejected.