The Research and Improvement of Microstrip Coupler's Directivity

• Main Authors: Chung-Ta Liu, 劉忠達
• Other Authors: Chi-Yang Chang
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/13347097613812995826

碩士 === 國立交通大學 === 電信工程系 === 90 === This thesis attempts to analyze and improve the microstrip coupler's directivity. In the research，there are two major innovations. The first one is to reduce the area of a weak coupler，the second one is to improve its directivity. As of saving the area of weak coupler，if we use the traditional coupled line coupler，the distance between the two coupled line would be very wide (a 35dB on a substrate of 25mil，εr =10.2, the distance would be around 80~90mil). After we inserted a central ground strip，we found the area of the weak coupler could be reduced significantly. As of improving the directivity of the coupler，if we twist the straight line to the S-shape，we could reduce the isolation to improve its directivity. Finally，we could combine the two innovations together to have better performance. Even if in the situation of weakly coupled，we could still have better directivity.