WordNet
n. an antenna that sends or receives signals equally in all directions [syn: nondirectional antenna]
Wikipedia
In radio communication, an omnidirectional antenna is a class of antenna which radiates radio wave power uniformly in all directions in one plane, with the radiated power decreasing with elevation angle above or below the plane, dropping to zero on the antenna's axis. This radiation pattern is often described as "doughnut shaped". Note that this is different from an isotropic antenna, which radiates equal power in all directions and has a "spherical" radiation pattern. Omnidirectional antennas oriented vertically are widely used for nondirectional antennas on the surface of the Earth because they radiate equally in all horizontal directions, while the power radiated drops off with elevation angle so little radio energy is aimed into the sky or down toward the earth and wasted. Omnidirectional antennas are widely used for radio broadcasting antennas, and in mobile devices that use radio such as cell phones, FM radios, walkie-talkies, wireless computer networks, cordless phones, GPS as well as for base stations that communicate with mobile radios, such as police and taxi dispatchers and aircraft communications.
Usage examples of "omnidirectional antenna".
Behind the crew cabin was the drivetrain and the power plant, thermal radiator wings, pressure tanks for consumables, and a small omnidirectional antenna that could transmit either to the orbital relay satellite or back to the habitat module.
Since the communications dish hadn't been deployed yet, we planned to use the omnidirectional antenna.
The suit sports high-intensity worklamps and a radio equipped with an omnidirectional antenna.
Its omnidirectional antenna had been replaced by a tweeter-like horn, and there were other changes I vaguely perceived but was not equipped to recognize.