Spoof Surface Plasmon Polaritons Based Reconfigurable Band-Pass Filter

This letter reports the design and analysis of the bandwidth (BW) reconfigurable band-pass filter using spoof surface plasmon polaritons at THz/microwave frequency. The designed filter consists of a spoof SPP T-shape resonator in which tuning has been introduced using variable capacitor device (having a cutoff frequency in THz regimes). Even and odd mode analysis has been carried out for a better understanding of the phenomenon. The proposed concept of variable bandwidth at a THz frequency in the SSPP structure has been demonstrated through Co-EM simulation. For the experimental validation of the proposed approach, the filter has been designed at microwave frequency, developed on a 60 mil (1.52 mm) thick microwave laminate, and characterized using a Keysight Field-Fox analyzer N9918A. In THz and microwave frequency regime, the designed filter has 3-dB BW reconfigurability of 20 GHz (0.41-0.43 THz) and 300 MHz (100-400 MHz) with the insertion loss of ~3 dB and ~1.7 dB-3.2 dB, respectively. The proposed reconfigurable bandpass filter will have an important role in the design and development of plasmonic circuits and systems.