Free-Space Measurement of Dielectric and Magnetic Properties by Double Planar Sample Method in Y-Band

Abstract

In this work, to measure the complex permittivity and the complex permeability of materials, the double planar sample method is proposed, which is a variant of the classical free-space measurement method. The device under test is a double planar sample instead of a single piece of sample. The greatest advantage of this method is that it eliminates complicated calibration in the measurement of the reflection coefficient. In this novel method, the reflection coefficient is replaced by a second transmission coefficient. Two groups of transmission coefficients are obtained by changing the distance between these double planar samples; then, the complex permittivity and the complex permeability by the transmission coefficient are retrieved. The relative uncertainties of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\varepsilon ^{\prime}$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu ^{\prime}$</tex-math></inline-formula> are both 1%. Four materials (polytetrafluoroethylene, silicon, quartz, and leaf of banana) are measured by this method, the results of which are consistent with those reported in the literature. The relative uncertainty of this method and the conventional free-space method is consistent. However, the magnetic loss tangent is very small, and the retrieval method is not sensitive to it.