Resonance parameter estimation for low-Q microwave cavities
Resonance parameter estimation for low-Q microwave cavities
复制标题
低 Q 值微波腔的谐振参数估计
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
G. Fischerauer
中科院分区：
文献类型：
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作者：
T. Jungkunz;G. Fischerauer
微波腔谐振器通常用于研究材料参数，因为后者强烈影响腔谐振。这种方法涉及从测量的n端口矩阵中提取谐振曲线特征，例如谐振频率或品质因子Q。在我们的应用程序中，我们的工作与2端口S-矩阵测量的自动矢量网络分析仪（VNA）。众所周知的特征提取方法包括仅幅度方法（3-dB方法、变换线性近似、非线性近似）和复值S参数的幅度和相位的拟合。这些方法通常应用于高Q谐振器，并且它们对于低Q情况的适用性不是先验的。我们遇到了这种低Q值的情况下，在原位观察电化学系统，如汽车催化剂，现在讨论相关的参数估计问题。我们解决的问题，S参数应该测量，他们应该如何评估和什么样的误差，e。例如，在一个实施例中，将谐振器离散化和嵌入其环境中是可以预期的。发现基于复数传递系数S12实现了最佳结果，因为这允许一定量的去嵌入并且对所检查的所有Q值都有效。
Microwave cavity resonators are commonly used to investigate material parameters because the latter strongly influence the cavity resonances. This approach involves the extraction of resonance curve features such as the resonance frequency or the quality factor Q from measured n-port matrices. In our application, we work with 2-port S-matrices measured by automatic vector network analyzers (VNA). Well-known feature extraction methods include magnitude-only approaches (3-dB method, transformed linear approximation, nonlinear approximation) and fits of the magnitude and phase of the complex-valued S-parameters. These methods are commonly applied to high-Q resonators, and their suitability for the low-Q case is not obvious a priori. We have encountered this low-Q case in the in-situ observation of electrochemical systems such as automotive catalysts and now discuss the associated parameter estimation problem. We address the issues of which S-parameters should be measured, how they should be evaluated and what errors due to, e. g., discretization and embedding of the resonator in its environment are to be expected. It is found that the best results are achieved on the basis of the complex transfer coefficient S12 because this allows a certain amount of de-embedding and works for all values of Q examined.