Air-Filled SSPP Transmission Line with Low Loss

Microwave transmission lines (TLs) based on spoof surface plasmon polaritons (SSPPs) have been increasingly used because of their advantage of strong field confinement, which leads to miniaturization and low crosstalk. However, this property also leads to higher dielectric losses, which cause the performance deterioration of the SSPP TLs. As a result, there is a conflict between dielectric loss and strong field confinement. In this paper, we propose a new SSPP TL structure, named as air-filled SSPP TL. The air-filled SSPP TL can substantially reduce the dielectric loss, since the waves propagate through the air rather than through a lossy dielectric medium. For comparison, a substrate SSPP TL with similar dispersion property to that of the air-filled SSPP TL is also designed. Simulated results indicate that the air-filled SSPP TL has lower losses.