Investigation of Corrected-Coefficient Binomial Impedance Transformer and Wide Stopband Lowpass Filter

• Main Authors: Chen, Yi-Nan, 陳奕男
• Other Authors: Tang, Ching-Wen
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/58495706986397319221

碩士 === 國立中正大學 === 電機工程研究所 === 100 === The study is based on the structure of planar microstrip line. It gets two parts, the first part propose a corrected method for impedance matching of quarter-wavelength transformer with binomial calculation method. It adds a correction coefficient K, by using it to adjust the impedance ratio to change the bandwidth of the circuit. In order to understand the effect of the transformer to bandwidth, the position of poles will also be analyzed and provide the diagram between correction coefficient and bandwidth. Finally, the verification of the theory will be realized with the wilkinson power divider. The second part is the design of lowpass filter with wide stopband. In this part, I will focus on the investigation of single filter with wide stopband. It has the ability of harmonic suppression, unlike traditional method using open stub to suppress the harmonic, it is a combing of two coupled line with different electrical length. By changing the characteristic impedance and coupling coefficient, the desired harmonic suppression will be achieved. In the experiment, I will use two design examples to verify the proposed analysis previously. A full-wave electromagnetic simulator is employed for this thesis. Moreover, these circuits are fabricated and measured. Well matched results between the simulation and measurement show the validity of all proposed circuits. Keywords – impedance transformer, power divider, filter, microstrip line .