W頻段導波管鰭線帶通濾波器改良設計及雙岔型雙工器設計

Abstract

本論文為開發W-頻段導波管鰭線帶通濾波器組裝結構之改良設計與W-頻段鰭線雙工器之實現與製作，本論文所選用的板材為Rogers RT-Duroud 5880TM，其基板厚度為5mil、介電常數為2.2、耗損正切為0.0009。濾波器設計程序為:首先先決定濾波器的中心頻率、比例頻寬、與濾波器階數。之後利用上述參數求得柴式低通原型濾波器之參數，再轉換成帶通濾波器各腔之間的耦合係數與外部品質因數。最後利用3D模擬軟體HFSS模擬組合之，如此整體濾波器架構得以實現。本論文中之濾波器有兩種中心頻率85GHz和94GHz。其中又分為單面式鰭線濾波器比例頻寬為3%的三階及四階鰭線濾波器，及雙面式鰭線濾波器比例頻寬為1%以及比例頻寬為3%之三階、四階鰭線濾波器，並導入所提的改良式組裝架構使其於實作量測時可以有更好的量測結果。在雙工器設計部分除了傳統T型架構，在本論文所使用為雙岔型(Bifurcated)架構，並設計85GHz-94GHz單面式3%三階之帶通濾波器，並利用電路模擬軟體ADS簡化我們的模擬流程，使模擬流程更為順利，並探討如何設計一種機殼使其通用於其他階數及單雙面式架構雙工器。

In this thesis, we develop the improved mounting structure of a W-band waveguide finline bandpass filter and realize the bifurcated finline diplexer. The proposed W-band finline bandpass filter are implemented with Rogers RT-Duroud 5880TM substrate with a dielectric constant of 2.2, a thickness of 5mil, and a loss tangent of 0.0009. The design procedures of the waveguide finline filter are briefly described as following. Firstly, decide the center frequency, the fractional bandwidth, and the order of filter. Then, obtain the Chebyshev low-pass prototype parameters, and transfer these low-pass prototype parameters into a series of coupling coefficients and external quality factor. Finally, by using the 3D EM simulation software HFSSTM get the physical dimensions of the filter. The finline bandpass filters are designed with the center frequencies of 85GHz and 94GHz. The filters are categorized as the unilateral finline filter with 3-orser and 4-order and a fractional bandwidth of 3%, and the bilateral finline filter with 3-order and 4-order and a fractional bandwidth of 1% and 3%. All of the filters are with the proposed mounting structure to improve the repeatability of the assembling process. Applying the bifurcated structure, we design a diplexer with center frequencies of 85GHz and 94GHz both with a unilateral 3-order and 3% filters. In order to improve the efficiency of simulation, we use circuit simulation software ADS combined with the HFSS to simplify our simulation process.