Realization of Rotman´s concepts of beamformer lenses and artificial dielectric materials

The Rotman lens as a passive beam former for antenna arrays and the artificial dielectric material, referred to recently as metamaterial, are two of the key concepts that Walter Rotman proposed. They made significant impact in the areas of antenna arrays and antenna and microwave components. This paper goes into the details of the realizations of the Rotman lens over the years, going from the waveguide-based to the printed-circuit configurations. The paper also discusses the results of some of the metamaterial implementations and features of antenna designs that use such materials.