As regards the wireless telegraph transmitter, one essential element is the antenna, aerial, or air wire, which may take a variety of forms. It may consist of a single plain or stranded copper wire upheld at the top by an insulator from a mast, chimney or building. The wire may have at the upper end a plate called a “capacity area,” electrically equivalent to an extension of the wire, or part of the wire may be bent over and carried horizontally. In many cases multiple antennae are used consisting of many wires arranged in cone or umbrella-rib fashion, or a metal roof or metallic chimney may be employed.