Triple‐mode bandpass filter based on short‐circuited patch resonator

• Main Authors: Qian Yang, Shuangyang Liu, Xinyue Dai, Hao Du, Cheng Guo, Anxue Zhang, Kai‐Da Xu
• Format: Article
• Language: English
• Published: Wiley 2021-07-01
• Series: Electronics Letters
• Online Access: https://doi.org/10.1049/ell2.12193

Abstract The letter presents a triple‐mode short‐circuited circular patch resonator for bandpass filter (BPF) design. The resonator employs the TM010 mode as its dominant mode, the resonant frequency of which is lower than that of the TM110 mode. In addition, four radial slots are etched on the patch to extend the current paths of the TM110 and TM210 modes, shifting down the resonant frequencies of the two modes. The adjacent triple modes can be used to design wideband BPF. Meanwhile, the centre frequency (CF) and bandwidth (BW) can be tuned by the length of the slots. Furthermore, the short‐circuited vias are arranged in a circle providing a tuneable parameter to control the CF and BW as well. According to the symmetry of the geometry, the resonator can be bisected to realise half‐mode resonance. Two cascaded half‐mode semi‐circular patch resonators are applied to design BPF with high selectivity. BPFs using the circular patch resonator and the semi‐circular patch resonator are designed and measured for demonstration.