以耦合諧振器實現微波分波與巴倫濾波器

Abstract

一段λ/4 (λ為中心頻率之波長)傳輸線的雙埠特性，可等效於諧振器間的電或磁耦合。本文以傳統Wilkinson分波器為基礎而發展，以λ/4步階阻抗諧振器做為電路元件，藉由適當調整耦合器間的配置距離，設計出需要的電磁耦合量，實現分波濾波器與巴倫濾波器電路。不僅施作容易，並且可有效縮小電路面積、節省成本。在電路效能方面，以中心頻率2.4 GHz電路實作的量測結果顯示，分波濾波器兩輸出埠之間的振幅誤差小於±0.5 dB、相位誤差小於±3°的工作頻寬，約可達200 MHz，-30 dB的截止頻帶大約可以擴展至4倍的基頻。而巴倫濾波器兩輸出埠之間振幅誤差小於±0.5 dB、相位誤差小於±3°的工作頻寬，約可達220 MHz，-30 dB的截止頻帶大約可以擴展至3倍的基頻。

A λ/4-transmission line (λ=wavelength at operation frequency) can be equivalent to the electric or magnetic coupling between two resonators. Based on the Wilkinson power divider, this thesis uses stepped-impedance resonators as building block. By adjusting the spacing between the resonators, adequate coupling can be achieved for design of power divider filter and balun filter. That is not only easy to implement but also having the benefit to miniaturization and cost down. The bandwidth of fabricated power divider filter with magnitude difference below±0.5 dB and phase difference below±3°about 200 MHz, and 30 dB stop band rejection up to 4fo.Furthermore, the bandwidth of fabricated balun filter with magnitude difference below±0.5 dB and phase difference below±3°about 220 MHz, and 30 dB stop band rejection up to 3fo.