一种高选择性的宽带滤波功分器

Design of wideband bandpass power divider with high rejection level stopband

为了实现无线通信系统的小型化,设计了一种同时具有滤波和功分功能的器件.将传统Wilkinson功分器中的两个四分之一波长传输线替换为两个具有带通响应的滤波器.同时,为了实现两个端口之间良好的隔离,将一个电阻安放在两个输出端口之间.利用奇偶模的分析方法,推导出了该滤波功分器的设计公式.实验结果表明,该器件的3dB带宽达到了62%,在低频段和高频段的抑制度分别达到了38.4dB和31.4dB(2.67f_0),该器件非常适用于小型化无线通信系统.

In order to reduce the size of communication system, a wideband filtering power divider with high rejection level in the lower and upper stopband is proposed in this paper. Two bandpass filters （BPF） are utilized to replace the quarter-wavelength transmission line in the traditional Wilkinson power divider. A resistor is adequately arranged for isolation and impedance matching. Even- and odd-mode method is applied to obtain design equations of the proposed circuit. Finally, a prototype power divider with central frequency of 2.97 GHz, and the fractional bandwidth （FBW） of 62% is designed and fabrica- ted for verification. Measured results indicate the attenuation level is larger than 38.4 dB in the lower stop- band, and larger than 31.4 dB （2.67 fo）.