不等功率耦合器暨步階式阻抗耦合線帶通濾波器之設計

Design of the Microstrip Couplers with Arbitrary Power Ratio and Microstrip Bandpass Filter with the Stepped Coupled Line

鄧跡寰(Chi-Huan Teng)

指導教授 ： 湯敬文

國立中正大學/工學院/電機工程學系/碩士(2013年)

摘要

本文分為兩大部分，第一部分利用並聯耦合線實現出一不等功率耦合器，並且在通帶內產生三極點來增加頻寬。與一般傳藍吉耦合器(Lange coupler), 平行耦合線耦合器相比，本電路的優點在不需要利用高阻抗傳輸線以及微小的耦合間距即可達到相同的特性, 而且在最後的量測結果中頻寬(FBW)達70%, 此外理論預測及量測間具有良好的一致性。
第二部分介紹一新型微帶線帶通濾波器，此濾波器由步階示阻抗耦合線以及兩根短路殘段所構成。每一段耦合線的電氣長度都經過設計及優化並且兩兩串連，以達到最大的諧波抑制，而且，弱強弱阻抗的耦合線，也具有抑制諧波的效果。位於輸入/輸出 端的短路殘斷，在通帶邊緣產生傳輸零點，增加頻寬選擇性，也增加了頻寬，最後就由模擬及量測比較圖可以發先其擁有良好的一致性。

關鍵字

弱強弱阻抗 ； 帶通濾波器 ； 頻寬 ； 並聯耦合線 ； 不等功率耦合器 ； 傳輸零點

並列摘要

This paper presents two designs. First, a novel design equations and examples of the modified arbitrary power ratio microstrip tandem coupler are presented. In order to obtain a wide passband, couplers with triple poles at the return loss are proposed. Compared to the conventional couplers such as Lange couplers and parallel coupled line couplers, high impedance transmission lines and narrow coupling gaps are not required for the proposed microstrip coupler. In terms of measured results, there is a wide bandwidth of more than 70%. Moreover, good agreement between theoretical predication and measurement validates our proposed structure.
In the second design, a novel wide passband microstrip bandpass filter with broader stopbands is provided. The proposed bandpass filters is composed of the stepped coupled line and two short-circuited stubs. Each stage of electrical length of the stepped coupled line has been optimized and cascaded together for harmonic suppression. Moreover, the stepped coupled line with weak–strong–weak coupling results in a wide stopband. Furthermore, with short-circuited stubs connected at the input/output port, there is a steeper passband skirt and broader passband. In addition, the agreement between theoretical prediction and measurement validates our proposed structure.

並列關鍵字

weak–strong–weak ； bandpass filter ； wide passband ； arbitrary power ratio microstrip tandem coupler ； transmission zero

參考文獻

[1] S. Niyogi, J. Scott, and K. Ghorbani, “RF vector sum phase shifter using a novel variable directional coupler, ” Asia-Pacific Microw. Conf., Hong Kong, 2008.

[2] K. Ghorbani, A. Mitchell, R. B. Waterhouse and M. W. Austin, “A novel wide-band tunable RF phase shifter using a variable optical directional coupler,” IEEE Trans. Microw. Theory Tech., vol. 47, no. 5, pp. 645-648, May 1999.

[3] P. Akkaraekthalin, C. Sawangnate, and V. Vivek, “Conductorbacked coplanar waveguide directional coupler and its use for a varactor-tuned 90◦ phase shifter,” IEEE APCCAS 2000 Circuits and Systems, 525–528, Tianjin, Dec. 2000.

[4] F. Ferrero, G. Jacquemont, “A tunable quasi-lumped microstrip coupler and RF applications,” IEEE MTT-S Int. Microw. Symp. Dig., pp. 1197-1200, 2007.

[5] H. Hayashi, M. Muraguchi, Y. Umeda, and T. Enoki, “A high-Q broad-band active inductor and its application to a low-loss analog phase shifter,” IEEE Trans. Microw. Theory Tech., vol. 44, pp. 2369-2374, 1996.