We explore limitations of cylindrical, convex Perfectly Matched Layer (PML) media. Although concave PMLs are routinely used in numerical electromagnetic (EM) simulations, convex PML media are of particular interest as possible blueprints for realizing EM absorber coatings. The design challenge however involves removing the gain medium behavior. As the paper’s central result we show that passive convex PMLs necessarily mandate an EM “horizon†in order to satisfy energy conservation.
