A Multi-Layer Spoof Surface Plasmon Polariton Waveguide With Corrugated Ground

Due to the unique properties of field confinement and enhancement, spoof surface plasmon polaritons (SPPs) are considered as special modes to break many challenges in traditional electronic and microwave engineering. Ultrathin corrugated metallic structure offers an easy fabrication method to realize spoof SPP waveguides on substrate, and has been proved to have many merits in recent years. Lately, a programmable and coding spoof SPP waveguide loaded by active elements was presented, which makes it possible to control SPPs in real time. However, this programmable SPPs waveguide suffers from the limited loadable space and hence can hardly achieve more complex controlling functions. On the other hand, the existing methods to excite spoof SPPs require large conversion structures, which are unadoptable in modern integrated circuits. In this paper, we propose a new type of spoof SPP waveguide composed of a metallic strip and corrugated ground with an open loadable space for large-scale and complex controlling networks. A new conversion structure is presented to achieve high-efficiency transition from the traditional microstrip to the SPP waveguide without using extra space. Both numerical simulations and experiments indicate the outstanding performance of the new spoof SPP waveguide. The proposed structure is also convenient to connect with active devices due to its multi-conductor nature. Hence, the proposed structure may find wide applications in SPP-based integrated circuits and systems in the future.