Analysis of a linear dipole antenna system for measurement the complex dielectric permittivity

In the paper, the use of linear dipoles for measuring the dielectric characteristics of subsurface media is examined. The given approach is based on the analysis of the mutual impedance of a system consisting of two linear dipole antennas and located above a surface of a layered half-space. The mutual impedance of two antennas depending on height above the surface and dielectric characteristics is investigated for the case of a homogeneous half-space in the 400 to 2000 MHz range. A measuring technique for the permittivity variations of homogeneous media is suggested. In addition, the influence of surface imperfections (deviations of the antenna heights from their nominal value) and dependence of calibration curves on the passive reactance in the measuring antenna are estimated. The comparison of theoretical and experimental results for the case of grey field soil with a rather uniform distribution of humidity is carried out.