微波印刷板电路基片复介电常数测量研究

Investigation on the Measurement of Complex Permittivity of Substrate of Microwave Printed Circuit Board

本文研究传输线法测量微波印刷板电路基片的复介电常数。该方法以矢量网络分析仪作为测量仪器,使用与同轴测量端口相匹配的带状线传输线作为待测结构。带状线的复介电常数信息反映在其特征阻抗和复传播常数中,特征阻抗和复传播常数可由其ABCD矩阵得到。由矢量网络分析仪测量得到的二端口散射矩阵(即S参数矩阵)可直接转换为ABCD矩阵,由此求出介质基片的复介电常数。为得到带状线正确的S参数,需要对测量系统进行校准。本文采用由TRL校准原理衍生而来的校准方法做校准。

In this paper the measurement of complex permittivity of substrate of microwave printed circuit board are investigated. Vector network analyzer （VNA） is used, and strip lines matched with co- axial line port are used as the structure to be measure. The information of complex permittivity of the strip line is included in the characteristic impendence and complex propagation constant of the strip line, which can be obtained from ABCD matrix. S parameters of the strip line can be measured by VNA, and they can be transformed into ABCD matrix, then the complex permittivity of the substrate can be ob- tained. To get correct results, the measurement system have to be calibrated. Here a calibration method result from TRL calibration principle is used.