An apparatus and related methods for controlling propagation of incident radiation are described. In one embodiment, the apparatus comprises a composite material operable to exhibit at least one of a negative effective permittivity and a negative effective permeability for incident radiation at an operating frequency. The composite material comprises electromagnetically reactive cells of small dimension relative to a wavelength of the incident radiation. Each of the electromagnetically reactive cells comprises first and second electromagnetically reactive segments microelectromechanically movable relative to each other according to an applied control signal such that at least one of a capacitive and inductive property of the electromagnetically reactive cells is temporally controllable according to the applied control signal.