W頻段導波管鰭線帶通濾波器設計

Abstract

本論文為設計W頻段中以導波管鰭線架構實現帶通濾波器的製作。導波管鰭線帶通濾波器的設計是決定中心頻率及比例頻寬後，將柴氏原型低通濾波器係數轉換成耦合係數與外部品質因素，利用3D模擬軟體HFSS模擬並萃取單一共振腔與外部訊源及二共振腔之間的耦合量，再加以整合來實現帶通濾波器的製作。論文中所實現的導波管鰭線帶通濾波器有兩種架構，分別為雙面式隔膜架構及單面式隔膜架構，雙面式隔膜架構設計了比例頻寬1%及比例頻寬3%，中心頻率在94GHz的帶通濾波器。而單面式隔膜架構設計了比例頻寬3%及比例頻寬8%，中心頻率在94GHz的帶通濾波器。論文中所實作之帶通濾波器電路皆使用基板厚度5mil，損耗較低的介電常數2.2的Rogers RT-Duroud 5880TM板材，其正切損耗為0.0009，完成的濾波器電路裝入特製的矩形導波管，可以得到良好的量測結果。

In this thesis, we use waveguide finline architecture to implement the bandpass filter design in W-band. The design of waveguide finline bandpass filter is firstly obtaining the Chebyshev low-pass prototype coefficients corresponds to filter specifications, and transferring these low-pass prototype coefficients into a series of coupling coefficients and the external quality factor. Then, the 3D EM simulation software HFSS is used to simulate single resonator and two coupled resonators to extract the external quality factor and the coupling coefficient respectively. Integrate each resonator with the proper external Q-factor and coupling coefficients finishes the bandpass filter design. Two finline filter structures, namely, the bilateral septum and the unilateral septum are designed and implemented. The bilateral septum structure is designed with a fractional bandwidth of 1% and 3 %, both with a center frequency of 94GHz. The unilateral septum structure is designed with a fractional bandwidth of 3% and 8%, both with a center frequency of 94GHz. The finlin filters are implemented with the Rogers RT-Duroud 5880TM substrate with a thickness of 5mil, a dielectric constant of 2.2, and loss tangent of 0.0009. Assembling the finline filter substrates corresponding to various filter specifications into the specially designed rectangular waveguide housing, the correct measurement results are obtained.