諧波抑制之微型化威爾金森功率分配器之實作及量測

本論文將此提出之微型化威爾金森功率分配器以頻率 0.9 GHz 做為中心頻率 設計，其需抑制三倍頻之諧振頻率2.7 GHz。透過上述介紹之設計流程，首先，先 選擇一個在小於電氣長度30°範圍內的電氣長度θo=15°，且諧振頻率之電氣長度為 θp=45°。接下來，分別利用 5.4 式和 5.9 式求出偶模阻抗 Zoe = 18.9 Ω和 Zoo = 13.6 Ω。然後，將得到之設計參數θo =15°、θp = 45°、Zoe = 18.9 Ω 及 Zoo = 13.6 Ω代入 5.5 式，計算出此電感電抗值 L = 9.95 nH。並從 5.6 式中，得知此微型化抑制諧波 功率分配器中連接兩輸出端埠之集總式隔離度電阻R = 100 Ω。最後，將透過這些 求得之設計參數利用安捷倫2009ADS 全波電磁模擬軟體 Momentum 以及 E5071C 網路分析儀圖分別去模擬及量測其S 參數。圖 5.6 表示為製作在 FR4 印刷電路板 上大小為32 mm × 30 mm 之微型化諧波抑制功率分配器，其面積為傳統威爾金森 功率分配器的65％，如表 5.1。其中，基板參數分別為下列三項︰介電常數為 4.33、

正切損耗為0.022 以及基板厚度為 1.6 mm。如圖 5.7(a)(b)(c)(d)所示，分別是端埠 1 之回授損耗S11、輸入端埠到輸出端埠之插入損耗S21、S31、端埠2、3 之回授損耗 S22、S33以及兩輸出端之隔離度S32。從圖5.7(a)(c)中可以發現每個端埠皆能匹配且 回授損耗小於 -20 dB，其中，S11 = -21.6 dB、S22 = -41.7 dB、S33 = -31.9 dB。在此 抑制諧波功率分配器中，觀察訊號在高頻諧波頻率時有無傳送至輸出端，如圖5.7(b) 表示插入損耗S21、S31在中心頻率0.9 GHz 時分別為 -3.3 dB 及 -3.5 dB。且在三 倍諧振頻率2.7 GHz 中，其插入損耗 S21、S31分別為 -44.8 dB 以及 -43.5 dB。圖 5.7(d)表示為兩輸出端之隔離度，其量測大小為 -28.6 dB。

圖5.6、微型化威爾金森功率分配器實照圖

表5.1、抑制諧波功率分配器之面積比較表

文獻 架構 面積比值

理想威爾金森功率分配器 四分之波長傳輸線

100

K.-H. Yi [8]

100

J.-S. Kim [31]

130

K.-K. M. Cheng [32]

130

P. Cheong [33]

60

This work

65

Mea S

(c)

(d)

圖5.7、微型化抑制諧波威爾金森功率分配器頻率響應 (c) 回授損耗 S22和S33(d) 隔離度

第六章 結論與未來展望

在本論文中所提出的多頻段、寬頻帶及微型化抑制諧波之威爾金森功率分配 器，都是近年來研究中很熱門之課題，也是為了無線通訊系統應用而發展。首先，

在第三章中，利用一種新穎的電磁能隙結構，使得威爾金森功率分配器在頻率上 的傳播常數受到能隙影響呈現一非線性趨勢，而利用此非線性特性可控制兩操作 頻率，使得第一操作頻率f1其電氣長度為β 以及第二操作頻率f2其電氣長度為3β， 達到雙頻段目的。其次，在第四章中，利用一耦合線短路之全通濾波器來實現雙 頻段目的以及使用兩條耦合線疊加之雙頻段功率分配器來實現寬頻帶之應用。其 中，在此雙頻功率配器使用兩操作頻率之電氣長度彼此互餘關係獲得雙頻段應 用。其次，在寬頻段的應用上，將兩設計頻率結合而達到一寬頻帶之威爾金森功 率分配器架構，且所需之寬頻帶設計參數能夠有足夠之自由選擇性，而降低在實 作上的困難度。最後，在第五章中，提出一種能夠任意選擇電氣長度的微型化諧 波抑制功率分配器。利用耦合線天生擁有的電容性並聯一微帶線電感性線段，來 獲得電容及電感並聯產生之共振結構，而得到諧波抑制之目的。除此之外，此微 帶線線段增加單一耦合線的電感性，而得到能夠縮小面積之應用，此微型化諧波 抑制功率分配器其面積小於傳統功率分配器達到百分之六十五。以上應用在多頻 段、寬頻帶以及諧波抑制之威爾金森功率分配器，在模擬及量測上皆有達到阻抗 匹配及高隔離度之目標，如表6.1。但是，應用在電磁能隙之雙頻段威爾金森功率 分配器卻因為能隙干擾問題，導致插入損耗之無法提升。除此之外，在抑制諧波 之微型化威爾金森功率分配器架構上，其提高電容性之關係，使得其架構需要由 低阻抗來實現。因此，未來可以朝著如何解決這所延伸之問題來解決，並得到一 種低插入損耗或是面積縮小之多頻段、諧波抑制之威爾金森功率分配器。

表6.1、特性綜合表

諧波抑制 3f0

S21：-44.8 dB S31：-43.5 dB

＊：量測之回授損耗(S₁₁)低於

-

＊＊：包括饋入線之電路主體

*＊＊：以操作頻率為標準

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