高选择性发夹型带通滤波器的设计

微带发夹型带通滤波器具有尺寸小、结构简单、性能稳定等优点,在射频微波领域有着广泛的应用。本文使用ADS 软件设计仿真了一种高选择性抽头式发夹型带通滤波器。与一般发夹型滤波器相比,该滤波器在输入输出端并联四分之一波长开路微带线,通过在寄生通带增加传输零点的方法提高滤波器的带外抑制性能。另外,在该滤波器的谐振单元上增加并联阶跃阻抗枝节,在通带两侧产生一对传输零点,来提高该发夹型带通滤波器的选择性。最后对这种高选择性发夹型带通滤波器进行实物加工,测试结果证实了该带通滤波器的良好选择性能。

Design of a Hairpin Bandpass Filter with High Selectivity

The microstrip hairpin bandpass filter has been widely used in RF and microwave field for its compactstructure and steady performances. This paper studies a hairpin bandpass filter with high selectivity by using ADS and thepassband range of the filter is 2 ~3GHz. Compared with traditional hairpin filters, microstrip lines of a quarter wavelength areused in both input and output of the filter, which improves the stopband rejection of the filter by adding transmission zeros inthe parasitic passband. In addition, a microstrip line of half wavelength is added on the resonator to improve the selectivity ofthe hairpin bandpass filter by generating a pair of transmission zeros at the two sides of the passband. Finally, the filter ismade for testing and the testing results show that the filter has a good selectivity.