Abstract: On the basis of the traditional NRW transmission and reflection method, an improved algorithm was proposed for measuring complex dielectric constant of non-magnetic materials. Two kinds of expressions was derived separately from the reflection coefficient and transmission coefficient, combined with the advantages of those two expressions, the problem of thickness resonance and multi-valued solution for the NRW algorithm was overcome, accurate results of the complex permittivity of the material was obtained.In addition, an original method was introduced to calculate the position of sample, and the location fuzziness problem due to movement of sample under test was overcome. Finally, a test software was compiled according to the proposed method, the comparative verification was completed by measuring the commonly used materials.

Key words: T/R method, Permittivity test, Non-magnetic dielectric material