Complex Permittivity Measurement of Paraffin Phase-Change Material at 26 GHz–1.1 THz Using Time-Domain Spectroscopy
Complex Permittivity Measurement of Paraffin Phase-Change Material at 26 GHz–1.1 THz Using Time-Domain Spectroscopy
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DOI：
10.1007/s10762-018-0556-5
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发表时间：
2018-11
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通讯作者：
Behnam Ghassemiparvin;N. Ghalichechian
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作者：
Behnam Ghassemiparvin;N. Ghalichechian
本文报道了在26 GHz-1.1太赫兹频率范围内测量六角烷薄膜的复介电常数。十六烷(C36H74)的熔点为75°C，体积变化为15%，这对于开发具有大位移的低损耗射频微致动器至关重要。在这项工作中，我们使用时间域谱测量石蜡样品在0.3-1.1太赫兹的频率范围内的传输系数。为了提取介电常数和准确估计小的损耗正切，我们建立了一个传播模型，通过一种新的最小二乘方法对测量数据进行拟合。采用德拜弛豫模型模拟介电常数与频率的关系。所描述的方法以最少的信号处理量快速收敛。通过为复介电常数的频率依赖关系设计合适的函数，该方法可以用来确定材料的复介电常数。测量了20个不同厚度的石蜡样品的透过率，其平均介电常数为2.25，标准偏差为0.028。损耗正切随频率单调增加，在1.1THz时最大值为6.32×10− 。我们的研究表明，石蜡是一种低损耗的介质，这使得它成为开发亚毫米和毫米波(MmW)可变电容、低损耗可重构天线和移相器的电热机械致动器的候选材料。
We report complex permittivity measurement of hexatriacontane films at the frequency range of 26 GHz–1.1 THz. Hexatriacontane (C36H74) has a melting point of 75 °C that exhibits a 15% volumetric change which is crucial in developing low-loss RF microactuators with large displacement. In this work, we employ time-domain spectroscopy to measure the transmission coefficient of the paraffin samples in the frequency range of 0.3–1.1 THz. In order to extract the dielectric constant and accurately estimate the small values of loss tangent, we developed a propagation model which measured data are fitted to through a new least-squares minimization method. A Debye relaxation model is used to model the frequency dependence of the permittivity. Described method is rapidly convergent with minimum amount of signal processing. This method can be used to determine the complex permittivity of the materials by devising an appropriate function for the frequency dependence of the complex permittivity. Transmission through 20 samples of paraffin with various thicknesses is measured and the average permittivity is found to be 2.25 with standard deviation of 0.028. The loss tangent is monotonically increasing with frequency and the maximum value is 6.32 × 10− 3at 1.1 THz. Our study demonstrates that paraffin is a low-loss dielectric which makes it an attractive candidate for development of electro-thermo-mechanical actuators for sub-millimeter- and millimeter wave (mmW) variable capacitors, low-loss reconfigurable antennas, and phase shifters.