可切换带宽的可调频率带通滤波器设计

提出了一种可切换固定带宽的可调频率带通滤波器新结构,且实现了在带宽切换前后都能保持固定带宽的特性。基于谐振线间的耦合系数提取算法,参考滤波器综合理论,设计并加工了工作频段为1.3～1.45 GHz的开环微带谐振可切换带宽的可调频率带通滤波器。测试结果表明,在整个工作频段内,3 dB 带宽在切换前后分别为120 MHz、100 MHz 和80 MHz,对应的插入损耗各是-2.9 dB、-2.4 dB、-2.6 dB,测试结果与仿真结果吻合良好。该滤波器具有结构简单、加工难度低、体积小、馈电控制简单等优点。

Design of a Switchable Absolute Constant Bandwidth Tunable Bandpass Filter

In this paper, a new structure is proposed for switchable constant absolute bandwidth frequency tunable bandpass filter, keeping the characteristics of absolute constant bandwidths before and after bandwidth switching. Based on coupling coefficient extraction method and filter synthesis theories,we designed and fabricated an open loop resonant microstrip tunable bandpass filer operating in 1. 3 to 1. 45 GHz with switchable bandwidth. The measurement results show the 3 dB passband bandwidth switches as 120MHz, 100MHz and 80MHz respectively in the operation frequency range, meanwhile the insertion loss is -2. 9dB, -2. 4dB, -2. 6dB correspondingly. Simulation results fit well with measurement results. The proposed filter has the advantages of simple structure, low fabrication difficulty, minimized size and convenient feed controls.