Multi-layer transmission line of spoof surface plasmon polaritons

In modern microwave technology, multi-layer structure is widely adopted in compact circuit design. In a multi-layer microwave system, the transmission line (TL) plays an important role. The multi-layer TLs need to have high cross-layer transmission efficiency, which is a big challenge in highly integrated circuits. Spoof surface plasmon polaritons (SSPP) possess good performance on field confinement and low transmission loss at microwave and terahertz frequencies, and can achieve the compact design in planar microwave circuits. In this article, a new type of multi-layer SSPP TL is proposed and tested. Taking advantage of the properties of SSPPs, the proposed TLs achieve high transmission efficiency for both in-layer and cross-layer situations. The proposed SSPP TLs have great prospect in the future multi-layer circuit design