Application of composite iron-containing material for shielding electromagnetic fields of ultra-high and higher frequency

Abstract

Changes in the transmission, reflection and absorption coefficients of electromagnetic radiation by composite
materials with a mass content of carbonyl iron of 40% and 60% in the dielectric matrix were investigated. It was found that the
transmission coefficients of electromagnetic radiation in the frequency range of 2–12 GHz decrease from 0.80–0.85 to 0.10–
0.30. Accordingly, the reflection coefficients of electromagnetic waves increase from 0.05–0.08 to 0.22–0.28. At the same time,
higher reflection coefficients are observed at frequencies of 8–10 GHz for samples with a lower content of carbonyl iron. In the
future, this indicator increases and stabilizes. The decrease in the reflection coefficient of electromagnetic waves with the content of a conductive substance in the dielectric material can be explained by the achievement of the percolation effect – an
increase in the conductivity of the material. This occurs when conductivity circles are formed in the material due to signifi cant
values of the electromagnetic constants of the filler particles. Therefore, when designing composite materials, one should be
guided by the volumetric content of the filler in the dielectric matrix. The obtained data allow one to calculate the complex
dielectric and magnetic permeability of materials. This will further simplify the design of composite materials with the required
protective properties. In the process of designing protective materials and structures, one should take into account the diff erent
dependences of the loss tangent angle for dielectric and conductive materials. This limit for compositions is somewhat conditional, therefore, a prerequisite for the development of protective materials is the determination of the amplitude -frequency
characteristics of the fields that require shielding.