A study on bandpass filter design using U-shaped stepped-impedance resonators

• Main Authors: Yong-Fong Chen, 陳永峰
• Other Authors: 張俊傑
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/82541344355478719017

碩士 === 國立臺灣海洋大學 === 電機工程學系 === 93 === The U-shaped stepped-impedance resonators have several advantages, such as low power loss and compact size, as compared with the conventional half-wavelength resonators. Furthermore, the defected ground structure not only can improve the performance of the filter, but also can furtherly reduce the size of the circuit. In this thesis, the U-shaped stepped-impedance resonators and the defected ground structures are used to design the bandpass filters. In this thesis, the influence of defected ground structure on the coupling and frequency response of parallel-coupled microstrip lines are studied firstly, and then the equivalent circuit of defected ground structure is derived. Next, the theory of the design of bandpass filter using U-shaped stepped-impedance resonators is analyzed, and the bandpass filters without or with defected ground structures are designed and realized, respectively. Finally, the characteristics of these two filters are measured and compared with the simulation results. From the analyzed results, it is found that both two bandpass filters have good performance. Furthermore, the size of the bandpass filter using U-shaped stepped-impedance resonators can be reduced about 28% as compared with the bandpass filter using U-shaped equal-impedance resonators. On the other hand, the size of the bandpass filter with defected ground structures can be reduced about 16% as compared with the bandpass filter without defected ground structures.