The design of a single-layer microwave absorbing material

Abstract

The microwave absorbing structure considered here consists of a homogeneous lossy dielectric material backed by a good conductor. Some previous work has been done on obtaining the electric and magnetic parameters of a suitable dielectric assuming that the magnetic dissipation factor was zero. With the wide spread use of ferrites at microwave frequencies, design information assuming a finite magnetic dissipation factor is needed and is presented. The special cases of zero electric dissipation factor, zero magnetic dissipation factor and equal electric and magnetic dissipation factors are also considered. Possible values of the electric and magnetic parameters of the absorbing material are obtained and the resulting thickness is presented. A method of choosing the parameters for the smallest thickness of dielectric is given. Little information has been available as to the possible band width of such a structure. An expression for the band width is derived for a given power reflection coefficient. The parameters of the absorbing material necessary for the greatest band width are indicated.