A compact microwave bandpass filter based on spoof surface plasmon polariton and substrate integrated plasmonic waveguide structures

作者：Luo, Yuxuan; Yu, Jiawei; Cheng, Yongzhi^*; Chen, Fu; Luo, Hui

来源：Applied Physics A: Materials Science and Processing , 2022, 128(2): 97.

DOI：10.1007/s00339-021-05250-w

• Microwave bandpass filter
• Substrate integrated plasmonic waveguide (SIPW)
• Spoof surface plasmonic polariton (SSPP)

A compact microwave bandpass filter with fishbone-shaped and hourglass-shaped groove structures based on substrate integrated plasmonic waveguide (SIPW) and spoof surface plasmon polariton (SSPP) is proposed and investigated. The dispersion and transmission characteristics of the proposed unit-cell structures of SSPP and SIPW were analyzed numerically, respectively. Numerical results indicate that the high and low cut-off frequencies of the bandpass filter can be independently adjusted by changing geometric parameters of unit-cell structures of SSPP and SIPW, respectively. The proposed microwave bandpass filter has a smaller electrical size because of its better electromagnetic (EM) field constraints than the traditional SIW ones with combed groove lines SSPPs. To verify the design method and concept, a microwave bandpass filter with fishbone-shaped and hourglass-shaped groove structures has been designed, fabricated, and measured. The results demonstrate that the proposed passband is in the range of 7.3-10.1 GHz, the return loss is higher than 10 dB and the insertion loss is less than 2 dB. The microwave bandpass filter is very compact in size, only about 0.99 lambda(0) x 0.35 lambda(0), where lambda(0) is the wavelength at the center frequency.