2450MHz介质复介电常数的测量

目的测量2450MHz频率下蒸馏水和不同浓度NaCl溶液的复介电常数,用以判定系统的可靠性和稳定性.方法根据微扰法得到复介电常数的测量公式,然后通过实验对已知参数的蒸馏水和NaCl溶液进行测量,并计算其复介电常数和电导率,验证计算结果的可靠性和稳定性.结果对计算结果进行统计分析和误差分析,其均值、标准差和变异系数表明,最终结果可与M.I.T标准较好地吻合.结论这种系统可较好地测量2450MHz频率下高损耗介质的复介电常数,测量系统的主要误差是由介质体积的误差引起的,因此精确测量介质体积是测量生物组织等高损耗介质复介电常数的关键.

A Measurement of Complex-permittivity of some Dielectric Materials at 2450MHz

Aim To measure the complex|permittivity of distilled water and various NaCl solutions at 2450MHz separately in order to determine the reliability and the stability of system.Method Based on measurement equations, which had been deduced by perturbational method. Subsequently, distilled water and NaCl solutions were measured with experiment. The parameters of the distilled water and NaCl solutions were known. Then the complex|permittivity and conductivity were calculated to verify the reliability and stability of the result.Result When statistical analysis and error analysis of the results were done, the mean values, standard deviations and coefficients of variation showed that the results complied with M.I.T standard quite well.Conclusion This system can measure the complex|permittivity of high|loss dielectric materials quite well at 2450MHz. The main error of the measuring system was caused by the error in volume of dielectric material. So measuring the volume of dielectric material accurately is the key of measuring the complex|permittivity of high|loss dielectric materials,such as biologic tissues.