全平面毫米波轉換器,濾波器及次諧波混頻器

Abstract

此研究提供一種新的毫米波電路設計方法，其最主要是利用多層結構來將微帶線和矩型波導同時結合於一印刷電路板上。我們設計了兩種Ka頻段之微帶線至矩型波導模轉換器：直接饋入型與直流阻斷型，同時我們為了量測方便而使其背對背相接。由量測結果可知直接饋入型與直流阻斷型此兩種模轉換器之反射損耗較-10 dB好的頻寬分別超過30 %和40 %，而其傳輸損耗分別為-0.8 dB和-0.56 dB。 為了展現此種模轉換器的可應用性，我們設計了兩種眾所週知在通訊系統中不可獲缺的元件：濾波器及混頻器。此Ka頻段濾波器原型包含有兩個上述的模轉換器和五個波導細長切口，利用模匹配方法來設計可以得到不錯的頻率響應。另外，在這個研究中也提出了利用一簡單之雙頻通道器來實現用於直接轉換接收器之次諧波混頻器的方法，由量測可知此次諧波混頻器在所設計的頻率有10.7 dB的轉換損耗，而射頻端和本地振盪源有超過30 dB的隔絕性。跟據這些研究中那些值得注意的有趣結果可以顯示利用傳統印刷電路板製程技術來實現射頻模組的方法是非常具有潛力的。

This paper presents a novel millimeter-wave design methodology, which applies a multi-layered structure to integrate microstrip and rectangular waveguide on the printed circuit board(s) simultaneously. Two kinds of microstrip-to-waveguide transi-tions such as direct-contact type and DC-block type, which all consist of two back-to-back connected mode converters, are built and tested at Ka-band. The meas-urement results of the direct-contact type and DC-block type indicate that the return losses are better than –10 dB with over 30 % and 40 % bandwidth and the insertion losses are –0.8 dB and –0.56 dB, respectively. To exhibit the applicability of the pro-posed microstrip-to-waveguide transitions, we develop two essential components known as filter and mixer, which are widely used at the communication system. The Ka-band filter prototypes, consisting of two planar mode converters and five waveguide slits, are analyzed by the mode matching method, showing a fair filter frequency response. An even quadrature harmonic mixer employing simple diplexer approach for direct conversion receiver is also presented in this paper. The measure-ment results demonstrate that the conversion loss of 10.7 dB and isolation of more than 30 dB between RF and LO can be achieved. Consequently, these attractive per-formances significantly show a great potential of implementing the multi-function RF modules by using conventional PCB (printed circuit board) fabrication process.