- 學位論文
探討增進同軸電纜至微帶線轉接之1-dB通帶頻寬
Enhancing of the 1-dB Passband of Coaxial-to-Microstrip Transitions
摘要
本論文主要是探討同軸電纜轉接到微帶線之傳輸特性，並提出一個新型的SMA接頭設計。主要目的為改善兩種傳輸線之間高頻的轉接效能以增進其1-dB通帶頻寬，此外本設計可適用於多層電路應用上。設計架構是在傳統凸緣固定式SMA接頭上加裝一個金屬套環，作為同軸電纜和微帶線二者之間的緩衝器，以降低在轉接處急遽電磁場型變化而導致的插入損耗。本設計使用以有限元素法為基礎的模擬軟體HFSS來進行模擬分析，並經由實作量測加以驗證結果。 本論文對此設計作特性評估，探討其由於製程中可能產生的誤差對傳輸特性的影響，並找出彌補方法加以改善。研究指出提出之轉接設計可適用於不同的微帶線基板，也可同樣應用於另一種常見之平面傳輸線即共平面波導之轉接。此外，本設計可進一步實行於不同種類的同軸電纜線與同軸電纜接頭，尤其是在高頻時常用之較小尺寸類型。上述這些特性證實本設計的廣泛適用性，特別在微波工程中較高頻的應用。
並列摘要
The thesis is mainly to research the the transmission characteristics of the coxial-to-microstrip transitions, and presents a new design for SMA connectors. The goal is to improve the transmission characteristics of the transitions at higher frequencies, and to become suitable for multi-layers circuits applications. A metallic ring is added to the conventional flange-mount SMA connector to serve as a buffer between the coaxial transmission line and the microstrip line. It could reduce the insertion loss of the transition caused by the sudden change of electromagnetic field distributions from one transmission line to another. The finite element method-based simulation tool, HFSS, is employed to conduct the required simulations and analysis for the proposed design, and through the measurement simulation results are validated. The thesis also evaluates the transmission characteristics of the proposed design for the transitions. Sensitivity study of the proposed transitions subject to fabrication errors is conducted, and solutions for some cases resulting in severe insertion loss are presented. The proposed design can equivalently work well on the transitions to microstrip lines with substrates of variable thickness and dielectric constant. It can also apply to the transitions to another commonly-used planar transmission line, coplanar waveguides. Besides, the design can be further extended to other connectors and coaxial cables as well, particularly those with smaller dimensions commonly used at higher frequencies. These characteristics demonstrate wide applicability of the proposed design, especially qualifications for many higher-frequency applications in microwave engineering.