利用雙路徑結構設計寬截止頻帶通濾波器

Design of Wide Stopband Microstrip Bandpass Filters with Two Path Structure

孫宇程(Yu-Cheng Sun)

指導教授 ： 湯敬文

國立中正大學/工學院/電機工程學系/碩士(2014年)

摘要

本篇論文主要是研究利用雙路徑結構，並將此方法應用在寬截止頻帶帶通濾波器的設計。本論文是利用平行耦合線電路來實現寬頻的架構，而且結合開路殘段與傳輸線的電路來達成寬截止頻帶的效果。至於在電路分析上，則可使用J反轉子的等效電路分析法。
本論文分為兩部分，第一部分提出雙路徑的傳輸線並結合在濾波器的設計中。由於在現有文獻中所提供的雙路徑方法僅能產生一個傳輸零點，在本研究中則是設計傳輸線的操作頻率，來產生二個傳輸零點以達到寬抑制頻帶的效果。在實作上將透過電磁模擬軟體並實現在PCB上。
第二部分則是改變雙路徑傳輸線架構成為雙路徑耦合線，並結合成三線耦合線的方式來實現。由於耦合線的本身的傳輸零點可以實現更寬頻帶的止帶，而且可以抑制耦合線所產生的寬頻諧波，因此設計將雙路徑耦合線搭配帶通濾波器來加以實現。其經由電磁模擬與量測的比較結果，可以得到良好的一致性。
上述電路均使用全波電磁模擬軟體IE3D進行模擬工作，並實際製作電路進行量測。最後經由電磁模擬與量測比較結果確實可以得到良好的一致性。

關鍵詞–雙路徑傳輸線、雙路徑耦合線、寬頻止帶、帶通濾波器、傳輸零點、諧波抑制。

關鍵字

雙路徑傳輸線、雙路徑耦合線、寬頻止帶、帶通濾波器、傳輸零點、諧波抑制

並列摘要

This study is the design of wide-band bandpass filters with dual-path structure. By using the parallel coupled lines, the bandpass filters with a wide passband have been realized. Moreover, the combination of open stubs and transmission lines, the bandpass filters with a wide stopband can be achieved. In addition, all proposed filters are analyzed with J inverters method.
In the first part, the two-path transmission line is provided for the design of bandpass filter. Different with the conventional two-path method which can generate only one transmission zero, the proposed method can generate two transmission zeros, and then a wide stopband will be obtained.
In the second part, the two-path transmission line is replaced with the two-path coupled line, and then cascaded with three coupled lines. Because of the multiple transmission zeros can generate by the couple line, the harmonics can be suppressed and a wider bandstop will come out.
All above mentioned circuits are simulated by using full-wave electromagnetic simulator IE3D, and the prototype of these circuits are fabricated and measured. The well-match results between electromagnetic simulation and measured data can evidence the availability of all proposed circuits.

Keywords – Two-path coupled line, two-path transmission line, wide stopband, bandpass filter, transmission zero, harmonic suppression.

並列關鍵字

Two-path coupled line, two-path transmission line, wide stopband, bandpass filter, transmission zero, harmonic suppression

參考文獻

[1] S. B. Cohn, “Parallel-coupled transmission-line-resonator filters,” IRE Trans. Microw. Theory Tech., vol. 6, no. 2, pp. 223-231, Apr. 1958.

[2] G.L.Matthaei, L.Young, and E. M. Jones, Microwave Filters, Impedance Matching Network, and Coupling Structures. Norwood, MA: Artech, 1980.

[4] B. Easter, and K. A. Merza, “Parallel-coupled-line filters for inverted-microstrip and suspended-substrate MIC’s,” in Proc. 11th Eur. Microw. Conf., Amsterdam, Netherlands, Sep. 7-11, 1981.

[5] C. W. Tang and Y. K. Hsu, “A microstrip bandpass filter with ultra-wide stopband,” IEEE Trans. Microw. Theory Tech., vol. 56, no. 6, pp. 1468-1472, Jun. 2008.

[7] W. Jiang, W. Shen, L. Zhou, A. M. Gao, W. Y. Yin, and J. F. Mao, “Design of compact dual-band quasi-elliptic filter with high selectivity and wide stopband rejection,” in Asia-Pacific Microw. Conf., Kaohsiung, Taiwan, Dec. 4-7, 2012, pp. 214-216.