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Design of a Tri-band Bandpass Filter Using Asymmetric SIRs for GSM,WiMAX and WLAN Applications

指導教授：管鴻 教授學生：蘇奕昕

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目錄

動機 非對稱步階式阻抗共振器特性 實驗結果與討論 結論 參考文獻

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動機

Multiple service technology is widely used to enhance the performance of the radio frequency (RF) devices in modern wireless communication systems.

GPS

Internet

GSM

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非對稱步階式阻抗共振器特性

R

RjYYin

2)tan)(cottan(cot2

1)tan(cot)tan(cot

2211

11222

t

2

21

2

R=Z2/Z1

共振條件 :

其中

非對稱步階式阻抗共振器示意圖

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實驗結果與討論

The proposed tri-band filter is designed at 1.8(GSM), 3.5(WiMAX) and 5.2GHz(WLAN) basically composed of two asymmetric SIRs and a pair of enhanced couple structures. The BPF is fabricated on the substrates of

Duroid 5880 with dielectric constant εr = 2.2, loss tangent δ = 0.0009 and thickness h = 0.787 mm.

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實驗結果與討論

It is clearly observed that the appearance of transmission zeros aside the second passband can be adjusted by the lengths of two enhanced coupling structure.

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實驗結果與討論

The first passband is properly determined while and G1=0.5 mm and L is fixed at 15.5 mm.

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實驗結果與討論

The measured results show the return loss |S11| of 20 dB, insertion loss |S21| of 1.8 dB and FBW= 11.1 % at 1.8 GHz, |S11| of 10 dB, |S21| of 2.8 dB and FBW = 6.2 % at 3.5 GHz and |S11| of 14 dB, |S21| of 1.9 dB and FBW = 6.1 % at 5.2 GHz.

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結論

A tri-band bandpass filter is proposed by using two asymmetric SIRs.

Three passbands are achieved by properly selecting the length ratio (α) and impedance ratio (R) of asymmetric SIRs.

The performance are well tuned by the lengths of two enhanced

coupling structure and gap of two asymmetric SIRs.

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參考文獻[1] M. H. Weng, H. W. Wu, and Y. K. Su, “Compact and low loss dual-

band bandpass filter using pseudo-interdigital stepped impedance resonators for WLANs,” IEEE Microw. Wireless Compon. Lett., vol. 17, no. 3, pp. 187– 189, Mar. 2007.

[2] M. H. Weng, H. W. Wu, K. Shu, R. Y. Yang, and Y. K. Su, “A novel tri- band bandpass filter using multilayer-based substrates for WiMAX,” 2007 European Microwave Conference (EuMC), Munich, Germany.

[3] Y. C. Chang, C. H. Kao, M. H. Weng and R. Y. Yang, “Design of the compact wideband bandpass filter with low loss, high selectivity and wide stopband,” IEEE Microw. Wireless Compon. Lett., vol. 18, no. 12, pp. 770- 772, Dec. 2008.

[4] George L. Matthaei, Leo Young, E. M. T. Jones, “Microwave filters, impedance-matching networks, and coupling structures.” McGraw-

Hill, New York.[5] J. S. Hong and M. J. Lancaster, Microstrip Filter for RF/Microwave

Application. New York: Wiley, 2001.