A compact multifunctional switchable filter based on parallel-coupled lines with three different filtering functions is presented in this letter. By using p-i-n switches to connect or disconnect microstrip line and shorted coupled lines, three different modes, i.e., wideband bandpass filter (BPF), bandstop filter (BSF), and dual-band BPF, can be realized. For demonstration, the switchable filter prototype is designed and fabricated. For the wideband BPF mode, the measured 3-dB fractional bandwidth is about 53.1% (1.41–2.43 GHz) with the measured insertion loss of 0.9 dB. For the BSF mode, the measured 10-dB fractional bandwidth is about 30.2% (1.63–2.21 GHz) with in-band suppression level of over 15.5 dB. For the dual-band BPF mode, the measured 3-dB bandwidths of the two passbands are around 3.8% and 2.7%, respectively.

中文翻译：

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使用耦合线结构的多功能可开关滤波器

在这封信中介绍了一种紧凑的多功能可切换滤波器，它基于具有三种不同滤波功能的并行耦合线路。通过使用引脚开关来连接或断开微带线和短路耦合线，可以实现三种不同的模式，即宽带带通滤波器（BPF），带阻滤波器（BSF）和双频带BPF。为了演示，设计并制造了可切换滤波器原型。对于宽带BPF模式，测得的3-dB分数带宽约为53.1％（1.41–2.43 GHz），而测得的插入损耗为0.9 dB。对于BSF模式，测得的10-dB分数带宽约为30.2％（1.63-2.21 GHz），带内抑制电平超过15.5 dB。对于双频带BPF模式，两个通带测得的3-dB带宽分别约为3.8％和2.7％。