阻带有衰减极点的微波带通滤波器

Microwave Bandpass Filter with Attenuation Pole in the Stopband

研究了阻带有衰减极点的微波带通滤波器的设计方法。从理论上证明了中间谐振器上加载电容器能在阻带低端形成衰减极点,并推导出计算极点位置的关系式。设计了中心频率为945 MHz的5级带通滤波器,它是由5个介质同轴谐振器和1块介质基片构成,第3个谐振器上加载电容,在915MHz处形成衰减极点。用rε=38的微波介质材料制成了实物,滤波器插入损耗小于2.5dB,915MHz处衰减大于62dBc,测量结果与设计相吻合。该滤波器已用于通信系统中。

The design of microwave bandpass filter with attenuation pole in the stopband was developed. The method which a capacitor was loaded to a intermediate resonator is proved to make a attenuation pole in the low stopband. The formula eaculating the position was induced. The five poles passband filter which center frequency is 945MHz was designed. It consisted of five resonators and one substrate. The 3rd resonator was loaded with a capacitor, the pole was located at 915MHz. The filter was made of microwave dielectric material of εr = 38, its insertion loss was below 2.5dB. The attenuation at 915MHz was more than 62dBc. The measurement result was consistent with the design. The filter was used in communication system.