A New Self-Packaged Substrate Integrated Air-Filled Spoof Surface Plasmon Polaritons Line With Inherent Low Loss and Deep Upper Frequency Suppression

In this article, a novel self-packaged substrate integrated air-filled spoof surface plasmon polaritons line (SPSIAF-SSPPL) with advantages of inherent low loss, low radiation, and deep upper frequency suppression is presented. This novel transmission line is based on the substrate integrated suspended line (SISL) technology and the spoof surface plasmon polaritons (SSPP) line of bow-tie cells. Parameter adjustments of bow-tie cells are corresponded to changes of the SSPP line cut-off frequency. In this article, an SSPP line and an SPSIAF-SSPPL structure with about 9.7-GHz cut-off frequency are designed, simulated, and fabricated. Simulated and measured results indicate that the loss and the near-field radiation of SPSIAF-SSPPL are greatly reduced compared with the SSPP line with identical parameters of bow-tie cells. Moreover, the proposed structure also shows a good performance on the suppression of the upper frequency. The measured stopband is extended from 10 to 15 GHz with the suppression level above 20 dB.