研究了变换比为4:1的宽频带传输线变压器,给出了考虑线圈互耦的等效电路模型,分析了其阻抗变换特性。针对在以往传输线变压器分析中忽略频率变化对磁导率的影响这一问题,以应用NiZn铁氧体的宽带传输线变压器为例,将频率变化对磁导率的影响应用到分析传输线变压器特性中。对测试结果的分析和比较表明:在传输线变压器输入阻抗的分析中,频率对其的影响是存在的,在等效电路模型分析中加以考虑,可以更好地与实际值吻合。

The broadband transmission-line transformer with 4:1 impedance transformation ratio is studied,its equivalent model with mutual coupling between transmission-lines is given,and its impedance transformation characteristics are analyzed. Then the permeability change with frequency neglected in conventional equivalent model is taken into account,and the property of the NiZn broadband transmission-line transformer is analyzed as an example. Result comparison between experiment and equivalent model analyses shows that the permeability change with frequency does have effect on analysis results,thus should be considered.