本文中，總共有四個電路。第一個電路就是帶止濾波器與寬頻帶通濾波器的切換，其中電路又可以分成多階(二階或三階)的設計以及對頻寬大小的設計，所以在這樣的設計下，總共可分成六個電路。第二個電路(可切換單頻/雙頻帶止濾波器設計)，則是利用帶止濾波器它的電氣長度可以對中心頻率調整及能改變止帶對稱性的特性來做切換設計。第三個電路(帶止濾波器與窄頻帶通濾波器之切換電路)，則是結合了窄頻帶通濾波器，是先將帶止濾波器轉換成兩組並聯的架構，再利用中間開路殘段的部分來設計帶通濾波器。而最後一個電路，則是用窄頻帶通濾波器它所具有不同饋入方式的特點來做切換。在板材的使用上，皆為FR4，厚度1.6mm，介電常數4.4，損耗正切0.0245。 ;This thesis used PIN diodes as the on/off switching component and utilized different pathways and boundary conditions to switch between two or more states on the same circuit. This study primarily uses band-stop filters (BSF) as the core of the passive circuitry along with ultra-wideband pass filters (UWBPF), narrow band-pass filters (NBPF), or multi-band stop circuitry to realize switchable circuits using specific design techniques. Since the BSF is the main component in the design of the switchable circuit and its structure is very similar to that of the UWBPF, an entire chapter is dedicated to its introduction and analysis.
In the present study, a total of four circuits are detailed. The first circuit switches between a BSF and an UWBPF. The circuit can be further divided into designs with multiple stages (two-stage or three-stage) and according to the size of the bandwidth for a total of six circuit designs. The second circuit (a single/dual-band stop filter switchable design) implements a switching design, which leverages the fact that the electrical length of the BSF can be used to adjust the center frequency and the symmetry properties of the stop band. The third circuit (a switching circuit for BSF and NBPF) is created by first converting the BSF to a design with two subcircuits in parallel and then utilizing the open stub in the middle to implement the NBPF. The last circuit uses the fact that NBPFs have different feed-in methods to implement switching. FR4 PCBs with a thickness of 1.6 mm, dielectric constant of 4.4, and a loss tangent of 0.0245 were used for all implementations.
