改进的同轴传输/反射法测量复介电常数

Determining complex permittivity with improved transmission/reflection method using coaxial line

推导了一种基于传输线理论和微波网络理论的测量电介质材料复介电常数的传输/反射法。给出了半波谐振和多值性问题的解决方法。改进的校准方法消除了试样位置和夹具长度测量误差对结果的影响。使用矢量网络分析仪和空气同轴线,在100 MHz～4 GHz频率范围内测量了聚四氟乙烯试样。计算值与参考值在整个频率范围内符合得很好,最大偏差不超过5%。实验结果表了明该文方法能够实现宽频带的电介质材料复介电常数的测量。

For determining complex permittivity of dielectric materials,a calculation algorithm of Transmission/Reflection method is derived from transmission line theory and microwave network theory.Solutions for half-wavelength divergence and multi roots problem are presented.A modified full 2-ports calibration is reported,which can eliminate the influence from the length of coaxial line and the position of sample.A PTFE sample had been tested using a vector network analyzer and a coaxial line from 100 MHz to 4 GHz.The results obtained by the presented method agree with the reference values with the max deviation 5% at all frequencies.The agreements demonstrate that the presented method in this paper can measure complex permittivity of dielectric materials efficiently in broad frequency range.