T.A. Pulko, N.V. Nasonova, M.V. Davydov, A.N. Osipov, L.M. Lynkov

In order to protect biological tissues as well as man-s organism totally against microwave radiation impact there is a strong need in novel protective means which are capable to attenuate electromagnetic radiation (EMR) and at the same time are compatible with man-s organism. The investigations in this area are aimed at biological tissues imitation using composite materials which can absorb electromagnetic radiation energy. Interaction between electromagnetic radiation and biological tissues at macrolevel depends on the dielectric permittivity and conductivity of the tissues. These properties characterize occurrence of bound charges (polar and non-polar macromolecules of various linear dimensions and water dipoles) and free charges (ions of extracellular and intracellular structures, polarized water molecules). The electric properties and the permittivity of man-s biological tissues possess dispersion ensured by charged particles state under impact of electromagnetic fields of various frequencies. This indicates that tissues polarization for various frequency ranges is ensured under different mechanisms, when orientation polarization of various cell structures and biological molecules is retarded with reference to electromagnetic field oscillation with minimum delay. Due to the capability of the biological tissues to absorb and to reflect the electromagnetic radiation we have developed composite liquid-containing structures to absorb microwave radiation and to imitate biological tissues under the electromagnetic radiation impact. We used capillary-porous fabrics 1.6 mm in thickness which are made of fiber materials with an average pore diameter about micron size. We impregnated them with aqueous solutions of metal salts and polymers in order to imitate the properties of the biological tissues. We have conducted a comparative analysis of electrical macroproperties of the obtained composite material with those of the biological tissues through the amplitude-frequency characteristic of impedance measuring in the fre-quency range from 20 Hz to 20 kHz. In addition we have studied the attenuation and reflection of the microwaves ensured by the composite and the tissues in the frequency range from 8 to 11.5 GHz using the VSWR and attenuation indicator. Through the transfer functions method we demonstrate that the nature of amplitude-frequency characteristics and the phase-frequency characteristics of the composite structures under study corresponds to the similar characteristics of the cutaneous and subcutaneous tissues. As the result we have obtained microwave shielding composite material with its impedance characteristics similar to the properties of the biological tissues and imitate cutaneous and subcutaneous coverings. The developed materials ensure the microwaves attenuation of 7-13 dB and the reflection of 3,8 - 1,8 dB in the frequency range of 8-11,5 GHz. Considering the above-said we suggest the materials application for human organism protection against microwave impact.