Techniques for measuring the dielectric properties of samples using coaxial-line and insulated antenna



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The theory of the coaxial-line-scattering-matrix method for measuring electromagnetic properties of solid and liquid samples is reviewed. The effect of the gap that inevitably exists between a rock sample and the coaxial-line sample holder is studied using computer simulations. The gap theory is corroborated by experiment. The coaxial-line method is also used to measure the electrical properties of Soltrol and an oil-base drilling mud. The measurement error due to the thin oil film which forms on the mud sample is analyzed. Charts are produced to correct for the gap error in the measured complex permittivity of rock samples. An inherent limit in the use of coaxial lines as sample holders for measuring liquid samples is studied. A method using an insulated antenna is introduced to overcome this limitation. An insulated antenna is designed and constructed to measure the electical properties of saline solutions. Solutions with concentration from 2.5 kppm to 56 kppm in the temperature range from 20[degrees]C (68[degrees]F) to 60[degrees]C (140 [degrees]F) are measured at 1.0, 1.1 and 1.2 GHz. The measured results are compared with Saxton and Lane's empirical formula and Schlumberger's EPT data.



Dielectric measurements, Rocks--Electric properties, Drilling muds--Electric properties