A new in situ procedure for measuring the dielectric properties of low permittivity materials

A novel in situ procedure for measuring the dielectric properties of materials with low complex permittivity has been developed. The dielectric probe is basically an open-ended coaxial line with an extended center conductor immersed in the material under test. The measurement technique utilizes a rigorous expression for the input impedance of the monopole probe and a complex zero-finding routine to determine the dielectric parameters of the material under test. Results of the uncertainty analysis are presented, together with experimental results for lossless and lossy low-permittivity materials. The complex permittivity results were within ±5% of the data available in the literature.