Dielectric Measurements in a Shielded Open Circuit Coaxial Line

A coaxial transmission line terminated by a shielded open circuit is convenient for dielectric measurements over a frequency range from quasi-static to microwave in a single sample holder. The transmission line analysis including the open circuit termination covered by lossy dielectric is outlined. Examples of measurements of known liquids are given. Errors may arise because the support bead of a coaxial connector may excite various-higher modes depending on the perfection of the symmetry and on the product frequency times refractive index of the sample. Criteria are given for the onset of higher modes.