omnidirectional antenna

An omnidirectional antenna is a radio antenna capable of transmitting and/or receiving radio signals from all directions of the sky which are visible from its location, simultaneously. Omnidirectional receiving antennas will be used in the next generation of instruments used for SETI and the study of short-duration or fast-changing natural sources. These revolutionary new instruments include the Allen Telescope Hectare Array, and the Square Kilometer Array. Omnidirectional transmitting antennas, if intended for communications with other technological civilizations in space, would require immense power in order to produce detectable signals at interstellar distances (see beacon, interstellar).