The many faces of the insulated antenna

The development of the insulated antenna is outlined from its beginnings as an ocean cable. The generalization of the theory from that applicable only to coaxial lines with an outer conductor of infinite extent to an insulated antenna embedded in a relatively dense medium that may be a dielectric or a conductor is described. The properties of the eccentrically insulated antenna and their usefulness in traveling-wave directional arrays for lateral-wave transmisson are reviewed. The diagnostic applications of the insulated antenna are considered with special reference to the measurement of the electric field in an ambient medium independent of its permittivity and to a study of the properties of a plasma-filled tube.