A probe antenna for in situ measurement of the complex dielectric constantof materials

A new probe for the in situ measurement of the complex dielectric constant of materials in the microwave frequency region is described. The probe uses two stub antennas mounted on a cylinder. The cylinder is inserted in the m aterial and the transmission coefficient between the two antennas is measur ed. By comparing this signal with that predicted from a numerical model of the probe obtained by the finite-difference time-domain (FDTD) method we ca n determine the dielectric constant of the material. The measurement setup and numerical model of the probe are described and several measurement exam ples in natural and artificial media are presented.