Groove Gap Waveguide Bandpass Filter Based on Spoof Surface Plasmon Polariton for Ka-Band Applications

In this article, spoof surface plasmon polariton (SSPP) is developed in a groove gap waveguide (GGW) to realize an adjustable bandpass filter for Ka-band applications. The proposed SSPP structure consists of a single row of corrugated metallic blocks, which is embedded into the groove of GGW. The lower cut-off frequency of the passband can be adjusted by changing the groove width or pin height, and the upper cut-off frequency of the passband is determined by the period or height of the SSPP unit cell through dispersion and ${S}$ -parameter analysis. For demonstration, a GGW-SSPP bandpass filter is fabricated and measured based on the proposed method. The measured bandwidth is from 29.8 to 35.8 GHz, which is in agreement with that of the simulated one. The proposed GGW-SSPP filter can achieve adjustable bandpass characteristics with a low insertion loss of 0.22 dB owing to the application of GGW.