Design and Calibration of a Large Broadband Dielectric Measurement Cell

A large dielectric measurement cell is designed and calibrated to operate over a 1 MHz-3 GHz frequency range. The cell is much larger than the commercially available cells and is useful for measuring samples with large-grain heterogeneities like concrete or rock. The cell works on a coaxial transmission line principle. Once the S parameters of the two end sections are calibrated, the S parameters of the sample region can be found. Then the complex permittivity of the sample can be de-embedded. Because of the broad frequency range, three calibration methods are used for low-, intermediate-, and high-frequency ranges. The accuracy of the cell is tested by measuring materials of a known dielectric constant. Error analysis is also performed to determine the uncertainty of the measurements.