應用於無線通訊系統之寬止帶與超寬頻響應微帶線帶通濾波器之研究

Study of Microstrip Bandpass Filter on Wide Spurious Suppression and Ultra-wide Band Response for Advance Wireless Communications

史帝文(Steve Ramirez Vargas)

指導教授 ： 廖慶聰

共同指導教授 ： 翁敏航

崑山科技大學/工程學院/機械工程研究所/碩士(2008年)

https://doi.org/10.6828/KSU.2008.00032

摘要

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關鍵字

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並列摘要

This thesis is divided into three parts: (a) design of microstrip bandpass filter with multiple order harmonic suppression; (b) design of dual-wide band bandpass filter and (c) design of ultra wideband (UWB) bandpass filter with narrow notch band.
A patch dual mode band pass filter is fabricated on Duroid 5808 substrate. The designed structure consists of circular shape allowing the same to reduce its size in relation to previous works. By using tapped inset input and output (I/O) lines a strong electrical coupling is achieved and the filter reaches a low insertion loss. In addition the performance of compact circular bandpass filter is improved by using a combination of structures over the I/O lines such as open stubs, spur line and Defect Ground Structure (DGS); which creates a wide spurious response suppression. Furthermore, DGS is characterized by having a stopband in a frequency range. The equivalent circuit can be modeled as a parallel resonance circuit and the parameters of inductance and capacitance can be extracted from the circuit. Experimental results show a good agreement with the simulated results.
Besides for the first time a novel compact microstrip bandpass filter with dual-wide passbands is designed. The filter consists of a ladder stub resonators to produce attenuation poles and form a low loss and dual-wide passband response. An equivalent transmission line model is elaborated and the corresponding impedance of the circuit is extracted as well. A 43% and 25% fractional bandwidth (FBW) at the two passbands are respectively achieved.
Finally, a compact ultra wide bandpass filter with embedded open stub for small band rejection is fabricated. The designed characteristics match the Federal Communications Commission (FCC) spectrum mask from 3.1GHz to 10.6GHz for UWB applications. This filter at center frequency f0 of 6.85 GHz has presented very good measured characteristics including low insertion loss, wide bandwidth and low group delay. A small bandwidth rejection at 5.8 GHz to avoid WLAN signal is created. The experimental results of the fabricated unit show a good agreement with the predicted results.

並列關鍵字

Bandpass Filter ； Circular Patch ； Ultra Wide Band ； Ring MMR

參考文獻

Chapter 1

[1] D. M. Pozar, Microwave Engineering, Second Edition. John Wiley & Sons, Inc., 1998.

[6] J. R. James and A. Henderson, “High-frequency behavior of microstrip open-circuit terminations,” IEE J. on Microwaves, Optics and Acoustics, vol. 3, pp. 205-218, Sep. 1979.

[10] D.C. Chang and C.W. Hsue, “Wide-band equal-ripple filters in nonuniform transmission lines,” IEEE Trans. Microave. Theory Tech., vol. 50, no. 4, pp. 1114-1119, Apr. 2002

[11] C. C. Chen, J. T. Kuo, M. Jiang and A. Chin, “Study of parallel coupled-line microstrip filter in broadband,” Microw. Opt. Tech. Lett., vol. 48, no. 2, pp. 373-375, Feb. 2006.