擴張式步階阻抗諧振器應用於堆疊帶通濾波器之諧波抑制

An Expanded Stepped Impedance Resonator Applied to Stacked Bandpass Filters for Spurious Suppression

本文提出一種擴張式步階阻抗諧振器，將步階阻抗諧振器之高阻抗傳輸線段由兩段傳輸線取代，低阻抗傳輸線段以環形耦合線取代，借此改變高次諧波頻率的特性，再配合外加之開路殘段抑制高次諧波。本項新式電路以傳輸線模式進行特性及等效電路分析，輔以高頻電路分析軟體IE3D取得結構參數變化對頻率響應之影響。文中並設計二個耦合堆疊步階阻抗帶通濾波器，並於內部空間中加入適當之開路殘段抑制諧波，模擬與量測結果相當一致。

In this paper, a novel expanded stepped impedance resonator is proposed. The circuit uses two transmission lines and a ring coupled-line to replace high and low impedance lines of the stepped impedance resonator. This act can expand the inner enclosed area of the stepped impedance resonator and change the frequency response in higher frequency bands, and after adding some open-stubs in the expanded inner area the harmonics supression showed great improvement. Using this new structure, two stacked bandpass filters were designed and measured. The measured results show very good agreement with the simulation results.