平面寬頻帶通濾波器設計

Design of a Planar Wideband Bandpass Filter

張祐瑄(You-Xuan Zhang)

指導教授 ： 翁偉中

國立暨南國際大學/科技學院/電機工程學系/碩士(2022年)

https://doi.org/10.6837/ncnu202200147

摘要

本文提出平面寬頻帶通濾波器，其具有縮小化以及寬頻的特性，使用一對1/4開路線，一對耦合線，倒 U 型結構諧振腔以及一個位於中心的開路截線為設計電路之基本架構，透過調整開路短截線來調整傳輸零點以及群邊的陡峭度，亦可調整通帶內的返回損耗，耦合線以及中間的倒 U 型諧振腔所組成的耦合結構可以形成寬頻特性，耦合線的間距固定在最小值 0.12 (mm) 以達到最佳的耦合效果。於實作上，使用便宜的玻璃纖維材質 (FR4) 板材來實現所提出之架構，經由模擬以及量測結果比較後，具有良好的一致性，量測的頻寬為 74.1 % ( 1.67 GHz - 3.45 GHz ) 且模擬與實測皆具有良好的頻率響應。
本文所提出的設計方法濾波器結構為多個開路截線的耦合結構所組成構造簡單；且通過調整其開路截線的長度，可以輕易控制其通帶的帶寬。總結以上所述，本文提出之設計方法具有容易設計且低成本等優勢。

關鍵字

帶通濾波器 ； 寬頻 ； 無線區域網路 ； 微帶線

並列摘要

This thesis proposes a planar broadband pass filter, which has the characteristics of miniaturization and broadband, using two pairs of open stubs, a pair of 1/4 wavelength coupling lines, an inverted U-shaped resonator and an open stub located in the center. The broadband characteristics with the steepness of the group edge of the filter can be achieved by adjusting the transmission zero points and the open stubs; the return loss in the passband can also be adjusted by the couplings composed of the 1/4 wavelength coupling lines and the inverted U-shaped resonators. In addition, the spacings between the coupling lines are fixed at 0.12 (mm), which is a fabrication limitation, to achieve the better coupling effects. After parametric studies in simulation, the filter was fabricated and measured. The results show that the specifications of the filter are achieved and good agreement between simulation and measurement is observed showing the validity of the design. The fractional bandwidth of 47.8 % (2.13 GHz - 3.42 GHz) is obtained. The proposed wideband bandpass filter has the advantages of being simple in structure, having an easy design, and being low cost. The filter is a good candidate for WLAN applications.

並列關鍵字

Bandpass filter ； wideband ； wireless local area networks ； Microstrip

參考文獻

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