具低通響應之微帶線至共面波導轉接器

Abstract

轉接器的設計在文獻中已存在許多相關實例，如各種類型傳輸線之間的轉接。設計轉接器的目的不外乎希望能量從不同傳輸線轉換的過程中穿透量達到最大且反射量則達到最小。在一般通訊系統中，低通濾波器常常被拿來用在抑制諧波或者不要的雜訊，因此低通濾波器的響應著重在小型化、低介入損失、高選擇性、較寬的截止頻帶…等。同時平面型的微波濾波器廣泛的被使用在微波系統之中，因為具有相當大的製作方便性。 通訊系統中非線性元件如功率放大器等經常在後面加上一個低通濾波器用來抑制不必要的諧波與雜訊，同時末端再經由天線輻射。本文討論微帶線與共面波導之間的轉接，並且同時結合低通濾波器特性，讓前級能夠接上以微帶線設計的功率放大器，後級則可以接上以共面波導設計的天線。

There are so many researches about the transition from the past decades . Transition about different transmission lines is one of the most important things. The object of designing a transition are trying to keep the power transmission maximum and to keep the power reflection minimum . In a general communication system , low-pass filters are put in the right place to suppress the harmonics and unwanted noises . Therefore low-pass filter’s performances are focused on miniaturization , low insertion loss , high selectivity , wideband rejection and so on . At the same time , planar microwave filters are widely used in microwave system , because it is easy and convenient to fabricate . In communication system , nonlinear circuit such as power amplifier often add a low pass filter behind to suppress harmonics and unwanted noises . Eventually radiate form an antenna . In this thesis , we discuss microstrip-line to CPW transition , combined with a low-pass filter characteristics in a single circuit . This circuit can be put between the microwave-fed power amplifier and a CPW-fed antenna .