In this paper, a highly sensitive octagonal spiral sensor is presented that can be applied to measure the permittivity of solid materials with high accuracy. Compared with the traditional split-ring resonator (SRR)-based configuration, the confinement of the electric field in the gap of the polygon spiral resonator can be improved by increasing the number of polygon sides, which leads to higher measurement sensitivity. By compromising between ease of processing and sensitivity improvement, an octagonal spiral structure is finally obtained. To determine the measurement sensitivity, a differential measurement scheme loaded with dual octagonal spiral sensors is adopted, and the sensor is modeled under the unloaded condition to confirm its designed operating frequency of 2.48 GHz. Then, experiments and corresponding simulations are implemented on loading with two different kinds of reference materials. The equivalent circuit model is obtained, and its results are compared with those from the numerical simulation. The sensor is fabricated on a 0.5-mm-thick Teflon substrate. Two of standard solid dielectric samples are tested using the proposed scheme, and their permittivity values are retrieved. The measured data are in agreement with the corresponding reference values available in the literature, with typical errors of less than 2%.

中文翻译：

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装有八边形螺旋谐振器的高灵敏度传感器，用于检索固体材料的介电常数

在本文中，提出了一种高灵敏度八角螺旋传感器，可用于高精度测量固体材料的介电常数。与传统的基于裂环谐振器 (SRR) 的配置相比，通过增加多边形边的数量可以改善多边形螺旋谐振器间隙中电场的限制，从而提高测量灵敏度。通过在易于处理和灵敏度提高之间进行折衷，最终获得了八边形螺旋结构。为了确定测量灵敏度，采用加载双八角螺旋传感器的差分测量方案，并在空载条件下对传感器进行建模，确定其设计工作频率为2.48 GHz。然后，实验和相应的模拟是在加载两种不同类型的参考材料时进行的。得到等效电路模型，并将其结果与数值模拟结果进行比较。该传感器是在 0.5 毫米厚的 Teflon 基板上制造的。使用所提出的方案测试了两个标准固体电介质样品，并检索了它们的介电常数值。测量数据与文献中可用的相应参考值一致，典型误差小于 2%。使用所提出的方案测试了两个标准固体电介质样品，并检索了它们的介电常数值。测量数据与文献中可用的相应参考值一致，典型误差小于 2%。使用所提出的方案测试了两个标准固体电介质样品，并检索了它们的介电常数值。测量数据与文献中可用的相应参考值一致，典型误差小于 2%。