Permittivity measurements using a short open-ended coaxial line probe

Improvements for permittivity measurements with short, open-ended coaxial line probes are achieved by using a more accurate formulation and by adding a finite conductor flange at the aperture of the probe. A conductor flange with a diameter of about 10 times the outer diameter of the coaxial line greatly improves the performance of the coaxial line probe. For a probe without a flange, a three-term admittance formula with calculated coefficients gives good measured results as compared to standards. However, for a probe with flange, a two-term admittance formula with a calibration coefficient gives better measured results.<>