Towards space-time metamaterials

Metamaterials may be generally classified in terms of the direct and indirect space and time, or space-time (ST), dependencies of their bianisotropic constitutive parameters. This classification leads to a set of 16 distinct types of metamaterials, among which those having time dependence have hardly been explored to date. This paper represents a step in the systematic investigation of media belonging to the uncharted territory of ST metamaterials, i.e. media with both space and time structure. It first establishes fundamental ST-media concepts and tools, next describes the physics and modeling of ST media made of abrupt and sinusoidal discontinuities, and finally presents a couple of related application examples.