A multiple input loop antenna comprising one or more half-loop antennas disposed above a ground plane wherein the plane of each half loop is perpendicular to the ground plane such that the multiple input loop antenna is a three-dimensional structure and electromagnetic waves are radiated from points within the volume occupied by the antenna rather than from a two-dimensional surface. For this reason, the multiple input loop antenna can radiate levels of peak power without inducing excessive air breakdown which are relatively high compared with peak power levels of conventional antennas having comparable transverse dimensions. Also described is an array antenna comprised of an array of multiple input loop antennas.