Abstract: The addition of semiconductor spacers into the spaces between the metal strips of a metal grid permits electron-hole plasmas to be introduced there controllably. Thus, the grid can be made to transmit or reflect an incident wave with a polarization perpendicular to the strips depending on whether or not the spacers are filled with minority carriers. The presence of carriers may be controlled electrically, optically and by field effect means which permit the basic metal strip/semiconductor structure (MGSS) to operate as a reconfigurable hologram, a reflector, a phase shifter, a switch, and a beam-steering antenna.