Comparative study of radiation enhancement due to metamaterials

Abstract

We present a comparative study on radiation enhancement due to metamaterial antenna substrates. The study is performed via electromagnetic inverse source theory and constrained optimization. The aim of the study is to understand the effect of reference antennas on enhancement level estimates. The geometry of the problem is that of a piecewise-constant, radially symmetric, three-region system (spherical core-shell system). Particular attention is given to the case when the core and the shell are made up of lossless materials having oppositely signed constitutive parameters.