抑制多重諧波的平行耦合微帶線濾波器設計

Abstract

本論文設計具寬廣上止帶的對稱二階微帶線濾波器，藉由抑制二、三、四倍頻諧波，達成寬廣的上止帶。輸出入級產生二倍頻的傳輸零點，由共振器耦合級產生三倍頻零點，此外再加上開路殘段來壓抑四倍頻諧波。為了縮小電路尺寸，使用Er = 10.2厚度h = 1.27 mm 的板材，可選擇使用對稱或斜對稱饋入，並可在通帶兩側產生零點。利用此一結構的二階濾波器就可抑制二倍頻、三倍頻和四倍頻響應。量測結果與模擬大致相符。

In this thesis, two-stage microstrip bandpass filters are designed to have a relatively wide stopband. The input/ output stages are designed to create a transmission zero to suppress the second harmonic. The coupled section of resonators is designed to generate a transmission zero to suppress the third harmonic. In addition, open stubs are added to suppress the fourth harmonic. For reducing the circuit size, a substrate with Er = 10.2 and thickness h = 1.27mm is used. This structure has two zeros beside passband which caused by symmetric tapped in or skew-symmetric tapped in. Based on this structure, two-order filters can suppress second, third and fourth harmonic response. Measured and simulated results have a good agreement.