Spoof surface plasmon polariton beam splitters integrated with broadband rejection filtering function

Abstract

In this paper, a new kind of spoof surface plasmon polariton (SSPP) beam splitter integrated with band-rejection filtering functions is presented. Firstly, the mechanism of single-band rejection phenomena of the SSPP transmission lines (TLs) with and without T-shaped decorations are revealed through dispersion analyses. Based on the single-band rejection filter, multi-band rejection filters are further designed by introducing different intervals between the symmetric T-shaped decorations. Furthermore, we construct a compact Y-shaped beam splitter integrated with a broadband band-rejection filtering function using the SSPP TLs, which consists of an SSPP TL with rectangular grooves and two filtering branch SSPP TLs. Multiple band-rejection integrated beam splitters can also be realized by incorporating different intervals between the T-shaped decorations. The integration of the SSPP beam splitter and band-rejection filter offers compact areas, lower insertion loss and controllable passband features. It is strongly believed that that the proposed idea will raise promising possibilities in the integration of multiple microwave functions in the same component, e.g. filtering antennas, filtering switches, multifunctional radiofrequency (RF) passive and active components capable of performing several RF analog signal-processing functions in the same circuit volume, and so on.