Abstract: A communications system is described which utilizes an antenna having means for selectively controlling the amount of incident electromagnetic energy directionally reflected therefrom. The antenna is comprised of a spherically configured array of conductors which focus incident energy on a reflector whose electrical conductivity characteristics and thus reflectivity characteristics can be controllably varied. The reflector can comprise a gas tube whose conductivity and thus reflectivity characteristics are a function of the number of ionized gas molecules therein. Modulation of the reflector reflectivity characteristics permits identification information, for example, to be impressed on the energy reflected therefrom.