Design and analysis of electromagnetic expanders and concentrators

A general description on the Electromagnetic (EM) concentrators/expanders with arbitrary shapes is proposed. A quantitative EM analysis is also given, which demonstrates that the magnitude of the magnetic field H´ (or electric field E´), the average Poynting vector S_av´, the phase velocity ν´, and the wavelength λ´ of a incident plane wave will change when it propagates in these devices. As devices with irregular structures may have inhomogeneous parameters, this paper also designs a trapezoid concentrator, in which all of the parameters are homogenous.