This article presents a dual-band bandpass (BP) to bandstop (BS) switchable filter with independently tunable center frequency and bandwidth. Two different length half-wavelength resonators are coupled with two separate coupling lines. Each resonator consists of a varactor-loaded stub at the center to tune the even mode frequencies, whereas two identical varactors are connected at the ends to tune odd and even mode frequencies simultaneously. The center frequency of the first passband is tuned from 1.03 to 1.4 GHz with constant fractional bandwidth (CFBW) of 3.4%, and second passband from 1.35 to 1.74 GHz with CFBW of 2%. BP to BS switching is achieved by connecting a p-i-n diode between input and output feedlines.

中文翻译：

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具有独立可调中心频率和带宽的双频带带通到带阻可切换滤波器

本文介绍了一种具有独立可调中心频率和带宽的双频带带通 (BP) 至带阻 (BS) 可切换滤波器。两个不同长度的半波长谐振器通过两条独立的耦合线耦合。每个谐振器由位于中心的变容二极管负载短截线组成，用于调谐偶模频率，而两个相同的变容二极管在两端连接以同时调谐奇模频率和偶模频率。第一通带的中心频率从 1.03 到 1.4 GHz 调谐，恒定分数带宽 (CFBW) 为 3.4%，第二通带的中心频率从 1.35 到 1.74 GHz，CFBW 为 2%。BP 到 BS 的切换是通过在输入和输出馈线之间连接一个 pin 二极管来实现的。