Wideband Filter With Controllable Notched Band Based on Fan-Shaped SIW and Spoof Surface Plasmon Polaritons

In this letter, we propose a broadband bandpass filter featuring controllable notch bands and a wide stopband, utilizing fan-shaped substrate integrated waveguide (FSSIW) and spoof surface plasmon polaritons (SSPPs). Rectangular slots arranged in a quasiperiodic pattern are carved into the central part of the upper metal of the FSSIW structure to support SSPPs mode. The dispersion curve of the quasiperiodic FSSIW-SSPPs unit structure is analyzed, which demonstrates that the quasiperiodic FSSIW-SSPPs unit structure is suitable for developing wideband bandpass filter. By modifying the geometric characteristics of the FSSIW and SSPPs structures, the lower and upper cutoff frequencies of the bandpass filter based on the Quasiperiodic FSSIW-SSPPs unit can be controlled independently. Utilizing the wideband bandpass filter as a foundation, coupling U-shaped resonators at the input and output terminals of the filter generates a notched band in the passband. The novel developed a wideband bandpass filter featuring a frequency notch that exhibits measured passbands spanning from 7.640 to 9.183 GHz and from 9.343 to 10.503 GHz. This filter with a notched band offers the benefits of compact lateral dimensions and a broad stopband.