Super compact dual-band substrate integrated waveguide filters and filtering power dividers based on evanescent-mode technique

Abstract

AbstractThis paper proposes a series of novel super compact dual-band substrate integrated waveguide (SIW) filters and filtering power dividers (FPDs) using two new compact metamaterial unit-cells. The proposed unit-cells, called COCSRRs, consist of a complementary split-ring resonator (CSRR) and an open CSRR (OCSRR). The working principle of the proposed filters and FPDs is based on the evanescent-mode technique.Based on the theory of evanescent mode, an additional passband below the waveguide cut-off can be achieved by etching the electric dipoles on the metal surface of the SIW structure. The CSRR and OCSRR unit-cells, behave as electric dipoles when excited by an axial electric field and are able to generate a forward-wave passband region below the cut-off frequency of the SIW configuration. Therefore, the proposed COCSRR unit-cells can be interpreted in term of electric dipoles, which can generate two forward-wave passbands below the cut-off frequency of the SIW structure. Although, the center frequencies of each passband can be independently controlled by changing the dimensions of the CSRR and OCSRR sections in the proposed COCSRR unit-cells. Accordingly, by loading the proposed COCSRR unit-cells on the waveguide surface, two arbitrary passbands below the waveguide cut-off frequency are achieved for WLANs and WiMAX applications. The designed SIW filters and FPD are fabricated and measured. Good agreement is observed between the simulated and measured results of the proposed filters and FPD. The proposed dual-band filters and FPD have many benefits like compact size, high selectivity, tunable passband frequencies, and easy integration with other planar technologies.