【作者】 张勇；

【导师】 刘策；

【作者基本信息】 长安大学 ， 交通信息工程及控制， 2014， 博士

【摘要】 近年来随着微波检测技术在道路工程领域中的应用，用于道路施工的岩石、沙子等非均匀混合介质介电特性的研究成为热点，非均匀混合介质测量理论也成为介电测量技术发展的一个重要分支。非均匀混合介质介电特性主要受界面极化影响，而界面极化发生频率范围较宽。因此，在不同频段对固体非均匀混合介质介电测量技术的研究具有重要意义。文章对固体非均匀混合介质在低频、射频和高频段的介电测量方法展开讨论。在低频段采用电容法，设计一款新型平板电容器。电容器测量原理是将测量样本看做电容和电导并联的等效集总回路，通过测量回路导纳得到样本介电常数。通过对传统电容器结构和算法的改进，提高电容器的测量精度。在射频段，从分析电极间场分布出发，根据似稳场理论建立极板间导纳的高阶场函数，通过计算贝萨尔零阶场和高阶场函数得到样本介电常数。此方法有效提高射频段电容器测量精度和测量频率上限，使得对非均匀介质宽频介电谱测量成为可能。在高频段,提出了基于微带线结构的谐振微带环和平行微带线的介电测量方法。微带环采用微扰原理。微带环紧贴测量样本，构成等效回路，样本介电常数差异会影响微带环电场分布，微带环的谐振频率与品质因数发生扰动，通过计算这种变化可得到样本的介电常数；平行微带线利用相位法，通过检测微带线插入样本前后相位的变化来计算样本的介电常数。平行微带线结构不同于传统的微带传输线结构，是将微带线底层的接地板改为与顶层相同的微带线结构，这种结构不仅保持微带线原有传输模式，同时增强边缘电场分布，从而提高测量分辨率和精度。与传统的平行线、同轴线、波导和谐振腔相比，这两种微带线结构的测量方法对样本尺寸加工精度要求低，适合固体材料测量。在较高频段，岩石等混合介质介电常数受其电导率的影响较小，因此，采用不同检测方法分别对沙子含水量，饱水砂岩孔隙度等物理参数进行实验测量，并对实验结果采用经验公式进行验证。在低频至射频段，采用平板电容器分别对用作路基的饱水岩石、油气岩石和泥质岩石的介电谱进行测量与讨论，对多弛豫过程和低频弛豫强度异常增大现象进行分析；对模拟路面结构的两相和三相平板电容模型的介电谱进行解析计算和实验测量，将计算值与测量结果进行比对分析。更多还原

【Abstract】 With the application of microwave nondestructive testing used in road works in recentyears, the research on dielectric properties of inhomogeneous complex media like rock andsand for road construction has become the focus. Inhomogeneous complex media for theresearch of dielectric measurement techniques provide an important branch. The dielectricproperties of inhomogeneous complex media are mainly influenced by the interfacialpolarization and the interfacial polarization always occurs in broadband. Hence, it is crucial toresearch on the dielectric measurement technology of solid inhomogeneous complex media indifferent frequency bands.This dissertation mainly introduces the dielectric permittivity measurement methods ofsolid inhomogeneous complex materials in different frequency bands. In LF band, thecapacitance method is used to design a new plate capacitor. In the capacitor, the measuredsamples are seen as the parallel lumped circuit of the equivalent capacitance and conductance.By measuring the admittance, the sample dielectric permittivity is obtained. With theimprovement of the structure and algorithm of traditional capacitors, the capacitormeasurement accuracy is improved. In RF band, according to the analysis of field distributionbetween the electrodes and the quasi-static field, a higher order function of admittancebetween the electrodes is established, and through calculating the zero order and higher orderBesar functions, the sample permittivity is obtained. The algorithm improves the measuringprecision of capacitor and the upper limit of measurement frequency, which makes themeasurement for the broadband dielectric spectroscopy of inhomogeneous media possible.In HF band, a micro-strip ring resonator and a parallel microstrip line both based onmicro-strip transmission line are presented. The microstrip ring is based on perturbationtheory. When microstrip ring closes to the sample to composite an equivalent dielectric model,the sample permittivity differences will affect the electric field distribution of microstrip ring,which will disturb the resonant frequency and quality factor of the microstrip ring. Inaccordance with the disturbance, the sample dielectric permittivity is obtained by calculation.Parallel microstrip line is based on phase. Through calculating the phase difference of microstrip line, the sample dielectric permittivity is obtained. Parallel microstrip line isdifferent from the traditional microstrip line, and the plate ground at the bottom layer ischanged to the strip line, same with the top layer. The structure not only keeps the originaltransmission mode of microstrip line, and the edge electric field intensity is increased, butimproves the resolution and the accuracy of measurement. Compared with the traditionalparallel lines, coaxial cable, waveguide and resonant cavity methods as well, the twoproposed microstrip line probes have low requirements for mechanical dimensions of sample,and are suitable for the measurement of solid materials.In the higher frequency range, the conductivity has little impact on dielectric permittivityof inhomogeneous complex media. Therefore, with different detection methods, the sandmoisture content, and the porosity of water saturated sandstones were measured, theexperimental results are verified by using the empirical formula. In LF and RF bands, used bythe plate capacitor, the dielectric spectra of the various rocks such as oil and gas bearing rocks,water saturated rock, and shaly rock as the rock subgrade are measured and discussed, themultiple relaxation processes and the abnormal rises in relaxation intensity at low frequenciesare analyzed. The dielectric spectra of two-phase and three-phase flat capacitor materials to beused to simulate of pavement structure are analytically calculated and experimentallymeasured, and the measurement results are confirmed by the calculated values.更多还原