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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
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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
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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
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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
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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