A numerical study is made of the bandwidth to thickness ratio of radar
absorbers for the suppression of normally incident waves. The study deals with
single- and multi-layer dielectric absorbers, in which the frequency dispersion of the
permittivity is allowed for. Analysis of the results permits obtaining a simple
empirical relationship between thickness, bandwidth, and reflectance level of some
specific kinds of absorbers. Essential features of different designs of dielectric
radar absorbers are revealed and discussed.