基于交指谐振结构的微带低通滤波器改进设计

提出一种微带低通滤波器改进设计方法.滤波器本身采用经典方法设计,通过在输入输出端口上添加交指型谐振器构成带阻滤波器,可将滤波器的适用带宽拓展50%以上.采用的交指型谐振器由8根容性交指和1根感性的高阻抗线并联而成,通过调整交指长度,可以方便地调节谐振器的谐振频率.设计并制作了两种改进结构,数值模拟和测量结果表明:通过引入交指结构,可以有效抑制微带低通滤波器的寄生通带,并且可以通过级联多个交指谐振器进一步扩展滤波器的适用频带.该设计方法还可用于带通等其他类型微带滤波器的寄生通带抑制.

Improved Design of Microstrip Low-pass Filter Based on Interdigital Resonator

An improved microstrip low - pass filter is proposed in this paper. The filter is designed by classical method with compact interdigital resonators at both input and output ports, which can extend the operating frequency bandwidth more than 50%. Each resonator consists of 8 interdigital capacitive fingers in parallel with a high -impedance straight line inductor, and it can be conveniently tuned at the desired resonance frequency by adjusting the finger length. The improved filer has been simulated, fabricated and measured. The results show that the proposed method can efficiently suppress the parasitic pass- band as well as extend the operating frequency bandwidth. The method can be also applied to band - pass filter design to suppress the parasite pass- band.