Now in the days of scientific advance it is impossible to lose an opportunity of research of nanotechnology. The systems of nanoparticles (NPs) embedded in various matrices are particularly promising. We demonstrate that it is possible to combine properties of polymers with conductivity and magnetization of metal NPs. Materials with metal NPs in polymer matrix were synthesized by decomposition of iron carbonyl in the solution-melt of polyethylene in oil. The many syntheses were held to create series of materials under equal circumstances but with different concentrations of NPs. As a result the series of samples with concentration from 1 up to 30 % (with 2-3% step) was obtained. Earlier the cavity perturbation method of measuring of complex dielectric permittivity and magnetic permeability was applied to investigate microwave electrophysical properties of nanocomposites. However, such research was held only for few samples with big step in concentration. Now the effects of concentration in polymer matrix and phase ratio of NPs on magnetic and dielectric permittivity and losses are presented. For characterization, we used TEM, XRD etc. The main major task is to determine the influence between the concentration of NPs, sizes, composition, and electrophysical properties. This work was supported by RFBR (04-03-32090, 04-03-32311, 04-03-32597, 05-03-32083), grant of the President МК-2733.2005.3 and the RAS program «Development of methods of synthesis of chemical substances and creation of new materials».