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微波工程期中報告 論文研討: Quarter-wavelength Resonator Bandpass Filter with Wide Stopband using Discriminating Coupling 作者： Yuan Chun Li *1, Xiu Yin Zhang *2, Quan Xue *3 出處： Proceedings of the Asia-Pacific Microwave Conference 2011 報告人: 碩研通訊一甲 MA130224 李堅誌 Southern Taiwan University Department of Electronic Engineering 摘要 A simple quarter-wavelength bandpass filter (BPF) with wide stopband is proposed. The harmonic suppression is achieved by discriminating coupling. Using an appropriate coupling region, coupling coefficient at the third harmonic is almost zero whereas that in the passband can be tuned to the desired value. An example filter is designed, manufactured and tested. The measurements show 20-dB rejection level from 1.16f0 to 6f0. It confirms the feasibility of the method. Index Terms — Bandpass filter (BPF), discriminating coupling, harmonic suppression. Proceedings of the Asia-Pacific Microwave Conference 2011 Yuan Chun Li *1, Xiu Yin Zhang *2, Quan Xue *3 1 分析BPF Fig. 1 illustrates the proposed wide stopband BPF. It consists of three/4 resonators. Appropriate coupling region is used to guarantee zero coupling coefficient at the unwanted passband The input and output are tapped at the resonators of both sides with characteristic impedance of 50 Electric coupling coefficient is a function of two coupling resonators’ electric field strengths as shown in (1) [14]. Proceedings of the Asia-Pacific Microwave Conference 2011 Yuan Chun Li *1, Xiu Yin Zhang *2, Quan Xue *3 2 電壓分佈 ■ Thus, the coupling coefficient between two resonators can be expressed in terms of voltage distribution because electric field is proportional to the voltage for quasi-TEM mode.Then, the coupling coefficient can be expressed as (2). Proceedings of the Asia-Pacific Microwave Conference 2011 Yuan Chun Li *1, Xiu Yin Zhang *2, Quan Xue *3 3 耦合係數 Fig. 3, the coupling coefficient of the fundamental mode will decrease as the gap width S1 increases; hence, the desired coupling coefficient in the passband can be attained by choosing an appropriate gap. The coupling coefficient of the third harmonic, is close to zero with little variation. It is concluded that the discriminating coupling can lead to the proper coupling coefficient in the designed passband while it can suppress the third harmonic effectively. Proceedings of the Asia-Pacific Microwave Conference 2011 Yuan Chun Li *1, Xiu Yin Zhang *2, Quan Xue *3 4 測量模擬結果 Fig. 5, the centre frequency of the proposed filter is 1.643 GHz and the fraction bandwidth (FBW) is 12.5%. The insertion loss is 1.5dB and return loss is greater than 15-dBwithin the passband. The spurious response is below 20-dB from 1.88 GHz to 10 GHz (1.16f0-6f0). That is, the thirdb harmonic is successfully suppressed in the design. It demonstrates that the proposed design procedure is effective for the third harmonic suppression. Proceedings of the Asia-Pacific Microwave Conference 2011 Yuan Chun Li *1, Xiu Yin Zhang *2, Quan Xue *3 5 結論 Proceedings of the Asia-Pacific Microwave Conference 2011 Yuan Chun Li *1, Xiu Yin Zhang *2, Quan Xue *3 心得 讀完這篇pdf檔後讓我了解到反射係數與阻抗匹配，正好 我剛碰上反射係數太高，但卻不太了解這是怎麼樣的一個 情況，不知道怎麼解決。但是剛好藉由這篇有提到阻抗匹 配後我在去取得其他資料後我已經把問題解決了。 Proceedings of the Asia-Pacific Microwave Conference 2011 Yuan Chun Li *1, Xiu Yin Zhang *2, Quan Xue *3