Cross-Coupled Four-Pole Bandpass Filter with Quarter-Wave Stepped-Impedance Resonators

• Main Authors: Mei Han Wang, 王玫涵
• Other Authors: J. T. Kuo
• Format: Others
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/10606981349993107611

碩士 === 長庚大學 === 電子工程學系 === 100 === Four-pole cross-coupled planar microwave bandpass filters are designed using four /4 stepped-impedance resonators (SIRs). The resonant frequencies of a SIR vary with impedance and length ratios of its low-impedance and high-impedance sections. Appropriate ratios can be chosen to maximize the upper rejection bandwidth. Given the passband function, the coupling coefficients between adjacent and nonadjacent resonators can be obtained for synthesis of the bandpass filter. Two transmission zeros can be realized by the cross coupling and improve the skirt selectivity of the filter. The full-wave simulator IE3D is used to design the resonators and to simulate filter performance. A bandpass filter with a bandwidth of 4% is designed, fabricated and measured. At last, shortage of bandwidth is compensated by tuning the coupling matrix. The measurement results for filters with and without compensation are presented and compared with the simulation data.