一种新的复介电常数自由空间测量技术研究

Analysis on a New Free-space Technology for the Measurement of Complex Permittivity

提出了一种新的复介电常数的自由空间测量方法，该方法将介质周期结构引入到复介电常数的测量中。运用多模网络理论与严格的模匹配技术，系统分析了加损耗样品层的介质周期结构的散射特性，详细研究了样品复介电常数对反射峰幅度和中心频率的影响。该测量方法不仅克服了传统自由空间法的不稳定性和相位模糊性问题，而且具有谐振法可以对低损耗介质精确测量ELN量过程简单的优点，为复介电常数的精确测量提供了一种新的测量方法和重要的理论指导。

A new free-space measurement for the complex permittivity is proposed. In this method, dielectric periodic structure （DPS） is introduced to the measurement of complex permittivity for the first time. The scattering characteristics of DPS added lossy sample layer are systemically analyzed by a method which combines the multimode network theory with the rigorous mode matching method： The effects of sample complex permittivity on the amplitudes and center frequencies of the maximum reflections are analyzed in details. The method not only overcomes the instability problem and phase-shift ambiguity which exist in the traditional free-space measurement, but also possesses the merit of cavity measurement technique which can accurately determine the complex permittivity of low lossy materials with simple measurement process. The research provides a new method and important theoretical guidelines for the accurate measurement of complex permittivity.