Complex permittivity and permeability of composite materials based on carbonyl iron powder over ultrawide frequency band

This is the final version. Available from the American Physical Society via the DOI in this record The complex electrical permittivity and magnetic permeability of composite materials made of a polymer binder filled with micron-scale carbonyl iron powder (CIP) are measured between 0.1 and 39 GHz. Permeability is measured in overlapping frequency subbands using two different techniques: a free-space method from 3 to 39 GHz and a coaxial impedance cell from 0.1 to 5 GHz. The dependence on filler concentration is studied for composites based on phosphated CIP R-100F-2. It is found that the static permittivity and permeability of the composites increase logarithmically with increasing percentage of CIP volume loading; this corresponds to Lichtenecker's law for a mixture of two components. It is demonstrated that by using the R-100F-2 type CIP it is possible to produce single-layer radar-absorbing materials with a relatively small thickness (less than 1.5 mm) and a deep and broad normal-incidence reflectivity minimum (less than -20 dB) from 10 to 30 GHz