圆柱腔宽带反相馈电模式滤波法研究

工作于TE01p模的圆柱腔具有高Q值低损耗的优点,但干扰模的存在使其宽频带的应用受到限制。文章在分析了圆柱腔中干扰模的场分布特点的基础上,设计了一种新的反射型馈电方式,采用宽带反相功分器将微波信号分两路馈入腔中,结合部分螺旋波导即可实现圆柱腔TE01p模式的纯净度。给出的测量结果表明,与采用传统直接馈电方式的谐振腔相比,在不损失品质因数的情况下,获得了良好的滤波性能。

A New Cylindrical Cavity Mode Filtering Method with Broadband Reversed-Phase Structure

Aim.The TE01p mode cylindrical cavity has very high quality factor(Q-factor),but its use on the broadband is not satisfactory because of the existence of disturbing mode.A new structure for filtering out disturbing mode is presented in some detail in the paper;microwave signal is divided into two parts completely reversed in phase and fed into a cavity;with the help of a part of helical waveguide,this structure obtains the purified TE01p mode in the whole working band.In this abstract,the following two topics are explained:(1) the principles of mode filtering,and(2) the measurement of the broadband reversed-phase structure.Topic 1 describes the method for restraining circumferential disturbing mode,which cannot be eliminated by the helical waveguide.In topic 2,the reflection coefficient and Q-factor of a cylindrical resonator with the new structure are measured.The measurement results and their comparison with other conventional structures,given in Figs.3 and 4 and Table 1,indicate preliminarily that the new structure effectively filters out all the disturbing modes except TE01p working mode and that the values of Q-factor measured for the new structure and other conventional structures are in good agreement.