In this article, an attractive resonant technique is devised for calculating the dielectric properties of arbitrary length material under test (ALMUT), which is partially filled inside a waveguide cavity sensor. The proposed technique exempts two major assumptions viz. the depolarization effect and the theory of images, which were neglected in earlier cavity perturbation methods. A numerical model of the depolarizing factor, which precisely considers the impact of the relative permittivity and the sinusoidal variation of the electric field, is also formulated. First, the technical modification and the numerical analysis are provided and after that, a new set of formulas for characterizing the complex permittivity of ALMUT is developed. The numerical results suggest the accuracy and validity of the scheme for a broad range of dielectric samples, including the typical case, i.e., the full-length dielectric sample. The novelty of the presented technique can be ascertained from the fact that it provides higher accuracy irrespective of the actual sample length when compared with standard cavity techniques. A few standard dielectric samples with the partially filled arrangement are measured using the WR90 cavity, and the results are compared with their corresponding values obtained using the earlier reported conventional and modified techniques. It is found that the results evaluated using the devised scheme are consistent and independent of the actual dimensions of ALMUT. On the other hand, error in estimated complex permittivity using the earlier reported approaches shows substantial dependence on the sample size.

中文翻译：

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用于任意长度样品介电测试的精确微波腔传感技术


在本文中，设计了一种有吸引力的谐振技术，用于计算任意长度的被测材料 (ALMUT) 的介电特性，该材料部分填充在波导腔传感器内部。所提出的技术免除了两个主要假设，即。早期腔微扰方法中忽略了去偏振效应和图像理论。还建立了去极化因子的数值模型，该模型精确考虑了相对介电常数和电场正弦变化的影响。首先，提供了技术修改和数值分析，然后开发了一套新的表征 ALMUT 复介电常数的公式。数值结果表明该方案对于各种介电样品（包括典型情况，即全长介电样品）的准确性和有效性。该技术的新颖性可以从以下事实来确定：与标准腔技术相比，无论实际样品长度如何，它都能提供更高的精度。使用 WR90 腔测量了一些部分填充排列的标准电介质样品，并将结果与​​使用早期报道的传统和改进技术获得的相应值进行比较。发现使用所设计的方案评估的结果是一致的并且独立于ALMUT的实际尺寸。另一方面，使用早期报道的方法估计的复介电常数的误差显示出对样本大小的极大依赖。