Analysis and Design of Compact Ultra-WidebandBandpass Filters Based on Three-Coupled-Line Resonator

• Main Authors: Wei-Cheng Lo, 羅偉誠
• Other Authors: Sheng-Fuh Chang
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/06301161028995787550

碩士 === 國立中正大學 === 電機工程所 === 94 === In this thesis, compact ultra-wideband bandpass filters base on to three-coupled-line resonator are investigated. First, the characteristics of three-coupled-line resonator are analyzed from the multiple-coupled-line theory, where the self and mutual capacitances of three eigen-modes( OE,EE, and OO mode )are derived and then the relationship between their characteristic impedances with the coupling coefficients is obtained. Second, the ultra-wideband bandpass filters based on the above derived relationship are designed. IE3D is used to include the parasitic effects. Three filters including the first-, second-, and the third-order topology are realized. The measurement results show that for the first-order filter, the insertion loss is 0.5 dB, and return loss is -15 dB from 3.1 to 5.1 GHz passband. Two transmission zeros are generated at 1.54 GHz and 7.07 GHz. For the second-order filter, the measured insertion loss is 0.7 dB, and return loss is 13 dB, and two transmission zeros located at 1.65 GHz, 6.9 GHz, respectively. For the third-order filter, the measured insertion loss is 2 dB, and return loss is 7 dB, and two transmission zeros located at 1.7 GHz, 7.1 GHz respectively. All these measurement results agree very well with the multiple-coupled-line theory and EM simulation. This shows great application potential of UWB bandpass filter designed based on the three-coupled-line resonator.