Abstract

The widespread use of anisotropic composite dielectric coatings operating in the microwave range in various science-intensive areas has led to the search and selection of effective methods for radio wave nondestructive testing of their electrophysical parameters. The existing approaches based on estimating the reflection and transmission coefficients of electromagnetic waves have low accuracy and reliability in assessing the components of the complex permittivity tensor and the thickness of such coatings and fail to take into account the frequency dispersion of these coatings and their placement on a metal substrate. In this paper, we propose an original method for local evaluation of the components of the complex dielectric permittivity tensor taking into account their frequency dispersion, as well as the thickness of anisotropic dielectric coatings on a metal substrate using radial surface electromagnetic waves of the microwave range. The method is based on solving inverse problems to determine the components of the dielectric permittivity tensor and the thickness of the coatings from the frequency and angular dependences of the field attenuation coefficient of the radial surface electromagnetic wave excited in the sample under study. The numerical and field experiments have shown that for a measurement frequency band of 9–13.5 GHz, the errors in the estimates of anisotropy coefficients are no more than 10% with a confidence level of 0.95. The statistical limit of the resolution of the magnitude off anisotropy in the dielectric permittivity is introduced and substantiated; this makes it possible to evaluate the ability of the method to distinguish two close values of any pair of components of the dielectric constant tensor. Numerical and field experiments have shown that the method can ensure estimation of these values when the difference between them is 0.2–0.3% or less in the frequency range of 9–13.5 GHz.

中文翻译：

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用表面电磁波法评估各向异性介电涂层的介电常数和测厚

摘要

各向异性复合介电涂层在各种科学密集领域的微波范围内的广泛使用，导致了对其电物理参数进行无线电波无损检测的有效方法的搜索和选择。现有的基于电磁波反射和透射系数估计的方法在评估复介电常数张量的分量和此类涂层的厚度时准确性和可靠性较低，并且没有考虑这些涂层的频率色散及其在涂层上的位置。金属基材。在本文中，我们提出了一种原始方法，用于对复介电常数张量的分量进行局部评估，同时考虑到它们的频率色散，以及使用微波范围的径向表面电磁波测量金属基板上各向异性介电涂层的厚度。该方法基于求解逆问题，根据在研究样品中激发的径向表面电磁波的场衰减系数的频率和角度依赖性来确定介电常数张量的分量和涂层的厚度。数值和现场实验表明，对于9-13.5 GHz的测量频段，各向异性系数的估计误差不超过10%，置信水平为0.95。介绍并证实了介电常数各向异性大小分辨率的统计极限；这使得评估该方法区分介电常数张量的任何一对分量的两个接近值的能力成为可能。数值和现场实验表明，当它们之间的差异在 9-13.5 GHz 频率范围内为 0.2-0.3% 或更小时，该方法可以确保对这些值的估计。