Analysis and Experimental Characterization of a Uniplanar Metamaterial-Inspired Substrate Integrated Waveguide for Easy-to-Implement mmWave Components

We fully explore the properties of a novel uniplanar metamaterial-inspired substrate integrated waveguide (SIW) for realizing easy-to-fabricate mmWave components. Conventional SIWs have a complex fabrication process, especially for higher frequencies, due to the need for drilling holes and injecting metallization. We substitute the vias of the conventional SIW with grounded single complementary split-ring resonators (CSRRs). We employ a coupled-mode theory framework to guide the waveguide synthesis and gain insight into the underlying physics of periodic grounded uniform and multi-element CSRR metasurfaces, that are the key elements of the corresponding CSRR SIWs. The CSRR SIW parameters are then fine-tuned by a more detailed FEM eigenmode solver. We verify the uniplanar single-CSRR SIW's merit and applicability by fabricating and experimentally characterizing the performance of a CSRR SIW waveguide section and antenna. The uniplanar single-CSRR SIW offers considerably simpler fabrication than both the conventional SIW and previously proposed CSRR SIW variations while maintaining performance. Compared to other SIW variations, the uniplanar single-CSRR SIW has a greater design flexibility, as we can change the number of CSRR rows and also use a non-uniform multi-element CSRR pattern to achieve advanced functionalities. The CSRR-SIW-based periodic leaky-wave antenna (PLWA) has competitive radiation characteristics and simpler fabrication than a corresponding SIW PLWA.