THE USE OF EMULSIONS TO REPRESENT DIELECTRIC MATERIALS IN ELECTROMAGNETIC SCALE MODELS

The electrical constitutive parameters of materials in a scale model and the corresponding full-sized system must satisfy certain relationships. Thus, it is desirable to have a series of materials with a range of electrical parameters or mixtures of materials with adjustable electrical parameters for use in scale models. Simple emulsions are examined as materials with adjustable electrical constitutive parameters. These emulsions are mixtures of oil, saline solution, and a suitable stabilizing agent (emulsifier). Since the relative permittivities of oil and water are around two and eighty, respectively, a large range of permittivity can be obtained for the emulsions. The conductivity of the emulsions can be adjusted by changing the normality of the saline solution. A series of oil-in-water emulsions (oil droplets in water), suitable for use in scale models, is developed; this includes the selection of an appropriate emulsifier. The electrical constitutive parameters of these emulsions are adjustable over wide ranges, and are predictable from a simple formula. As an example, an emulsion that is a scale model for red-clay earth is described. This emulsion matches the electrical constitutive parameters of the clay, including the dispersion in the conductivity, over a ten-to-one frequency range. © 1990 IEEE