Directional Antenna

A directional antenna or beam antenna is an antenna which radiates greater power in one or more directions allowing for increased performance on transmit and receive and reduced interference from unwanted sources. Directional antennas like Yagi-Uda antennas provide increased performance over dipole antennas when a greater concentration of radiation in a certain direction is desired.

All practical antennas are at least somewhat directional, although usually only the direction in the plane parallel to the earth is considered, and practical antennas can easily be omnidirectional in one plane.

The most common types are the Yagi-Uda antenna, the log-periodic antenna, and the corner reflector, which are frequently combined and commercially sold as residential TV antennas. Cellular repeaters often make use of external directional antennas to give a far greater signal than can be obtained on a standard cell phone. Satellite Television receivers usually use parabolic antennas.

For long and medium wavelength frequencies, tower arrays are used in most cases as directional antennas.

Other articles related to "directional antenna, antenna, directional, antennas":

Air Traffic Control Radar Beacon System - Theory of Operation - The Reply - Side Lobe Suppression
... The SSR's directional antenna is never perfect inevitably it will "leak" lower levels of RF energy in off-axis directions ... elicit a reply from their transponders when the antenna is not pointing at them ... This pulse is transmitted from the omnidirectional antenna (or the antenna difference channel) by the ground station, rather than from the directional antenna (or the sum channel) ...
... operated by Cogeco, it broadcasts on 106.9 MHz using a directional antenna with an average effective radiated power of 60,000 watts and a peak effective radiated power of 100,000 watts (class ... watts and a nighttime power of 5,000 watts as a class B station, using a directional antenna with slightly different daytime and nighttime directional patterns in order to protect various other stations on that ... watts and a nighttime power of 2,500 watts as a class B station, using a directional antenna with slightly different daytime and nighttime ...
... The station broadcasts using a two-tower directional antenna 24 hours a day ... WSHY has a construction permit to operate using a non-directional antenna (one tower), with daytime power of 270 watts and nighttime power of 28 watts ... only during daytime hours, using a non-directional antenna ...
Traffic Collision Avoidance System - TCAS Basics - System Components
... Antennas The antennas used by TCAS II include a directional antenna that is mounted on the top of the aircraft and either an omnidirectional or a directional antenna mounted on the bottom of the aircraft ... Most installations use the optional directional antenna on the bottom of the aircraft ... In addition to the two TCAS antennas, two antennas are also required for the Mode S transponder ...