存在干扰模式时的微波谐振器Q值计算方法  

Measurement of the Unloaded Q-factors of Microwave Resonators in the Presence of Coupling Modes

作　　者：吴昌英[1] 张悦诚 丁卓 韦高[1] WU Chang-ying;ZHANG Yue-cheng;DING Zhuo;WEI Gao(School of Electronics and Information,Northwestern Polytechnical University,Xi'an 710129,China)

机构地区：[1]西北工业大学电子信息学院,西安710129

出　　处：《微波学报》2023年第1期85-89,共5页Journal of Microwaves

摘　　要：谐振法测量介质介电常数时需要计算谐振器的无载Q值。当微波谐振器的工作模式受干扰模式影响时,会导致无载Q值的计算出现偏差。文章针对这种情况提出了一种存在干扰模式时计算微波谐振器无载Q值的迭代算法。该方法基于所提出的反向叠加和同相叠加两种等效电路模型,以传输系数模值平方之差在所有频点的平方之和作为目标函数,采用尺度变换最速下降法进行迭代。将圆柱形金属谐振腔的高Q值TE011模作为工作模式、简并的低Q值TM111模作为干扰模式,通过仿真和实测对该方法进行了验证。实测结果表明,当干扰模式较强时,3 dB法计算的工作模式Q值偏离真值14%,而所提出的迭代法的计算结果偏离真值不到1%。The unloaded Q-factor is needed when measuring the permittivity of the sample under test in a resonator.In the presence of a coupling mode,the mutual coupling of the two modes influences on the measured unloaded Q-factor.In this paper,an iterative method is proposed to calculate the unloaded Q-factor of the concerned mode with a nearby coupling mode.Two possible coupling mechanisms,in-phase coupling and out-phase coupling,are investigated.The sum in the frequency domain of the squared of the difference of squared module values of transmission coefficient is used as the objective function of the scaled steepest descent method.In the simulation and measurement,the high Q TE011mode of a cylinder resonator is considered as the concerned mode,and the degenerated low Q TM111mode the coupling mode.The measurement results show that 3 dB result is deviated from the true value by 14%,while the deviation of the proposed iterative method result is less than 1%with strong mutual coupling.

关 键 词：微波谐振器 Q值 等效电路 模式 迭代法 

分 类 号：TN751.2[电子电信—电路与系统]