在本論文中，我們提出一種具有諧波抑制效果的雙頻帶帶通濾波器的設計方法。首先，利用步階阻抗共振器來實現雙頻帶的基本架構。其次，藉由適當地設計共振器的架構，可以抑制產生在通帶外的諧振頻率以完成具有寬止帶的雙頻帶帶通濾波器。其止帶可以延伸至12GHz 並具有至少20dB以上的諧波抑制能力。此外，零度饋入的架構可被用來進一步改善此雙頻帶帶通濾波器的選擇性。最後的量測結果與全波模擬的結果相當一致。

A method for designing dual-band bandpass filters (BPFs) with harmonic suppression has been presented in this thesis. The stepped impedance resonators (SIRs) are used to achieve dual-band performance. By properly transforming the resonators into some equivalent circuits, several higher order spurious resonance frequencies may be suppressed so that a dual-band BPF with wide stopband can be realized. The stopband of the proposed dual-band BPF is extended up to 12GHz with a rejection level better than 20dB. Besides, 0° feed structure can be used to further improve the selectivity of the dual-band BPF. The measured results are in good agreement with the full-wave simulation results.

[1]. “Federal communications commission (FCC), code of federal regulations (CFR), title 47 part 95, MCIS band plan,” URL: http://www.fcc.gov, Mar 2003.
[2]. E. A. Wolff and R. Kaul, “Microwave Engineering and Systems Applications,” 2nd Edition, New York J. Wiley, pp. 605-621, 1988.
[3]. F. C. Chen and Q. X. Chu, “Novel Multistub Loaded Resonator and Its Application to High-order Dual-band Filters,” IEEE Trans. Microw. Theory Tech., vol. 58, no. 6, pp. 1551-1556, Jun 2010.
[4]. R. Ludwig and P. Bretchko, “RF Circuit Design: Theory and Applications,” Prentice Hall, 2000.
[5]. D. M. Pozar, “Microwave Engineering” John Wiley & Sons, Inc., 1998.
[6]. J. S. Hong and M. J. Lancaster, “Microstrip Filters for RF/Microwave Applications,” John Wiley & Sons, Inc., 2001.
[7]. P. H. Deng, N. I. Lai, S. K. Jeng, and C. H. Chen, “Design of Matching Circuits for Microstrip Triplexers Based on Stepped-impedance Resonators,” IEEE Trans. Microw. Theory Tech., vol. 54, no. 12, pp. 4185-4192, Dec 2006.
[8]. C. F. Chen, T. Y. Huang, C. P. Chou, and R. B. Wu, “Microstrip Diplexer Design with Common Resonator Section for Compact Size but High Isolation,” IEEE Trans. Microw. Theory Tech., vol. 54, no. 5, pp. 1945 –1952, May 2006.
[9]. R. Levy, “Direct Synthesis of Cascaded Quadrupled (CQ) Filters,” IEEE Trans. Microw. Theory Tech., vol. 43, no. 12, pp. 2940-2944, Dec 1995.
[10]. R. M. Kurzok, “General Four-resonator Filters at Microwave Frequencies,” IEEE Trans. Microw. Theory Tech., vol. 14, pp. 295-296, 1966.
[11]. R. Levy, “Filters with Single Transmission Zeros at Real or Imaginary Frequencies,” IEEE Trans. Microw. Theory Tech., vol. 24, no. 4, pp. 172-181, 1976.
[12]. J. S. Hong and M. J. Lancaster, “Design of Highly Selective Microstrip Bandpass Filters with A Single Pair of Attenuation Poles at Finite Frequencies,” IEEE Trans. Microw. Theory Tech., vol. 48, no. 7, pp. 1098-1107, Jul 2000.
[13]. J. S. Hong and M. J. Lancaster, R. B. Greed, and D. Jedamzik, “Highly Selective Microstrip Bandpass Filters for HTS and Other Applications,” Proceedings of The 28th European Microwave Conference, Oct 1998.
[14]. C. F. Chen, T. Y. Huang, and R. B. Wu, “Design of Dual- and Triple-passband Filters Using Alternately Cascaded Multiband Resonators,” IEEE Trans. Microwave Theory Tech, vol. 54, no. 9, pp. 3550-3558, Sep 2006.
[15]. J. T. Kuo and H. P. Lin, “Dual-Band Bandpass Filter with Improved Performance in Extended Upper Rejection Band,” IEEE Trans. Microwave Theory Tech, vol. 57, no. 4, pp. 824-829, April 2009.
[16]. P. Mondal and M. K. Mandal, “Design of Dual-Band Bandpass Filters Using Stub-Loaded Open-Loop Resonators,” IEEE Trans. Microwave Theory Tech, vol. 56, no. 1, pp. 150-155, Jan 2008.
[17]. M. Makimoto, “Bandpass Filters Using Parallel Coupled Stripline Stepped Impedance Resonators,” IEEE Trans. Microwave Theory Tech., vol. 28, no. 12, pp. 1413-1417, Dec 1980.
[18]. M. Sagawa, “Geometrical structures and fundamental characteristics of
microwave stepped-impedance resonators,” IEEE Trans. Microwave Theory Tech., vol. 45, no. 7, pp. 1078-1085, Jul 1997.
[19]. C. F. Chen, T. Y. Huang, and R. B. Wu, “Design of Microstrip Bandpass Filters with Multiorder Spurious-mode Suppression,” IEEE Trans. Microwave Theory Tech, vol. 53, no. 12, pp. 3788-3793, Dec 2005.
[20]. W. H. Tu, and K. Chang, “Compact Second Harmonic-suppressed Bandstop and Bandpass Filters Using Open Stubs,” IEEE Trans. Microwave Theory Tech., vol. 54, no. 6, pp. 2497-2502, Jun 2006.
[21]. M. L. Chuang and M. T. Wu, “Miniaturized Ring Coupler Using Multiple Open Stubs,” Microwave and Optical Technology Letters. vol. 42, no. 5, pp. 379-383, Sep 2004.
[22]. C. M. Tsai, S. Y. Lee, and C. H. Tsai, “Hairpin Filters with Tunable Transmission Zeros,” IEEE MTT-S International Microwave Symposium Digest, vol. 3, Aug 2001, pp. 2175-2178.
[23]. C. M. Tsai, S. Y. Lee and C. C. Tsai, “Performance of a Planar Filter Using a 0o Feed Structure,” IEEE Trans. Microwave Theory Tech., vol. 50, no. 10, pp. 2362-2367, Oct 2002.
[24]. L. H. Hsieh, and K. Chang, “Tunable Microstrip Bandpass Filters With Two Transmission Zeros,” IEEE Trans. Microwave Theory Tech., vol. 51, no. 2, pp. 520-525, Feb 2003.