Absorption spectrum of magnetically structured emulsions in the centimeter range

Abstract

The high degree of absorption of microwave radiation by composite materials with developed morphology can be significantly improved by directly changing the geometrical parameters of the subwavelength structure, which is difficult in the case of solid-state materials. In this work, a new composite liquid material with controlled absorption properties, a magnetodielectric emulsion, is investigated. The control of microgeometry parameters is accomplished through exposure to a magnetic field. The experimental studies have shown that the formation of chain structures from spherical water droplets in the composite leads to a significant change in the absorption coefficient. Thus, for an emulsion with 10% water content, exposure to a magnetic field of 25 kA m−1 increases the absorption coefficient by 400% at a radiation frequency of 10 GHz. It is noteworthy that the efficiency of the absorption properties control depends on the volume concentration of droplets in the sample and has a non-monotonic character. To interpret the obtained results, numerical modeling of the studied system in the effective medium approximation was carried out.