Diplexer Based on Surface Plasmon Polariton-like Propagation Induced by Structural Dispersion of Substrate Integrated Waveguide

In this paper we propose a novel diplexer based on surface plasmon polariton (SPP) like propagation in substrate integrated waveguide (SIW). The diplexer consists of two two-layer SIW filters, where layers are designed to have effective permittivities of opposite signs in a certain frequency ranges, thus providing SPP-like propagation, and consequently passbands and stopbands in the desired frequency ranges. The diplexer is designed to operate at 2.4/2.6 GHz, and it is characterized by high performance, low-profile and low-cost structure.