中文摘要：

测量介电常数对微波能应用有着十分重要的意义。终端开路的同轴线法是应用最多且有效测量介电系数的方法之一,而常规的测量探头很难区别出低耗物质的微弱介电常数变化。为了提高传统测量探头的测量灵敏度,本文提出了一种新型的谐振结构用以测量2.45GHz物质的介电常数,所提出的结构能够通过其电场汇聚效应增强传统测量探头对低损耗物质的感知能力。通过时域有限差分方法仿真计算了加载及未加载谐振结构的模型,结果表明提出的谐振结构能够有效地提高传统探头的灵敏度。通过搭建实验测量系统,研究三种类型的低损耗物质（煤,沙和土壤）,仿真结果和实验结果表明,本文提出的谐振结构具有一定的可行性和可靠性。

英文摘要：

Permittivity measurement of materials is important to microwave energy application. The open-ended coaxial line method is one of the most popular and effective means for permittivity measurement. However, the conventional coaxial probe is found difficult to tell small permittivity variations for low loss media. Novel resonance structure is proposed to improve the measurement sensitivity of traditional coaxial probe in permittivity measurement at 2.45 GHz. For low loss media, the sensibility of conventional coaxial probe is enhanced via electric field concentration generated by the resonance structure. Finite difference time domain method is used for calculating the model with and without the proposed structure. The optimized results show that the sensitivity of conventional probe can be improved greatly with the additional structure. An experiment system is constructed and three type low loss media （coal, sand and soil） are measured with both probes. The experiment results are agreed with simulations well which verify the new additional structure reliable and feasible.