A Resonant-Cavity Method for Measuring Dielectric Properties at Ultra-High Frequencies

The effect of sample wall gap on dielectric measurement of circular-coaxial cell

“…Some methods are destructive, i.e., drilling a core sample to fit inside a coaxial line [9], and * Mark of Schlumberger others are nondestructive [10,11]. The measurement principle can be based on resonant cavity, such, or broadband nonresonant structures [10,12,13].…”

“…A common example is the coaxial structure, which can be modeled as Transverse Electromagnetic (TEM) mode [12]. However, to perform measurement at subsurface conditions, closed waveguide and cavity structures have the advantage [10,11]. Due to the porous nature of reservoir rocks, the dielectric properties are frequency and temperature dependent [1].…”

Dielectric measurements using a reentrant cavity :

“…Many radio-frequency applications require an accurate value of the component of the permittivity normal to the plane of the material. The reentrant cavity is unique since it is possible to accurately measure materials at frequencies from 100 MHz to 1 GHz with axial electric field [1,2]. The reentrant cavity consists of a coaxial line or other transmission line with end walls, and a gap in the inner electrode where a sample is positioned.…”

“…Two approaches have been used for modeling the reentrant cavity. The first is a lumped-circuit approximation [1,2]. The other approach, which we develop in detail, is a rigorous mode-matching technique [3][4][5].…”

Dielectric and magnetic measurements from -50�C to 200�C and in the frequency band 50 MHz to 2 GHz

“…Coaxial probes and coaxial lines operate in the required frequency band and must be considered in this study. Tinga [6] is a lumped-circuit approximation [21,22]. The other approach is to solve for the fields by a rigorous mode-matching technique [23,24].…”