Directional antenna

A directional antenna or beam antenna is an antenna which radiates or receives greater power in specific directions allowing increased performance and reduced interference from unwanted sources.

Antennas can be designed to transmit and receive radio waves in all horizontal directions equally (omnidirectional antennas), or preferentially in a particular direction (directional, or high-gain, or “beam” antennas).

Directional antennas provide increased performance over dipole antennas—or omnidirectional antennas in general—when greater concentration of radiation in a certain direction is desired.

Dipole antennas (or such designs derived from them, including the monopole) are used to feed more elaborate directional antennas such as a horn antenna, parabolic reflector, or corner reflector.

The most common types are the Yagi antenna, the log-periodic antenna, and the corner reflector antenna, which are frequently combined and commercially sold as residential TV antennas.

A log-periodic antenna (LP), also known as a log-periodic array or log-periodic aerial, is a multi-element, directional antenna designed to operate over a wide band of frequencies.

The most common types are the Yagi antenna, the log-periodic antenna, and the corner reflector antenna, which are frequently combined and commercially sold as residential TV antennas. There are many ways to make a high-gain antenna; the most common are parabolic antennas, helical antennas, yagi antennas, and phased arrays of smaller antennas of any kind.

A Yagi–Uda antenna, commonly known as a Yagi antenna, is a directional antenna consisting of multiple parallel elements in a line, usually half-wave dipoles made of metal rods.

The most common types are the Yagi antenna, the log-periodic antenna, and the corner reflector antenna, which are frequently combined and commercially sold as residential TV antennas.

A corner reflector antenna is a type of directional antenna used at VHF and UHF frequencies.

Cellular repeaters often make use of external directional antennas to give a far greater signal than can be obtained on a standard cell phone.

A donor antenna can be any of several types, but is usually directional or omnidirectional.

Satellite Television receivers usually use parabolic antennas. There are many ways to make a high-gain antenna; the most common are parabolic antennas, helical antennas, yagi antennas, and phased arrays of smaller antennas of any kind.

Parabolic antennas are used as high-gain antennas for point-to-point communications, in applications such as microwave relay links that carry telephone and television signals between nearby cities, wireless WAN/LAN links for data communications, satellite communications and spacecraft communication antennas.

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

Tower arrays are used to constitute a directional antenna of a mediumwave or longwave radio station.

The most common types are the Yagi antenna, the log-periodic antenna, and the corner reflector antenna, which are frequently combined and commercially sold as residential TV antennas.

When a higher gain antenna is needed to achieve adequate reception in suburban or fringe reception areas, an outdoor directional antenna is usually used.

Directional antennas provide increased performance over dipole antennas—or omnidirectional antennas in general—when greater concentration of radiation in a certain direction is desired.

There are many ways to make a high-gain antenna; the most common are parabolic antennas, helical antennas, yagi antennas, and phased arrays of smaller antennas of any kind.

The antenna functions as a directional antenna radiating a beam off the ends of the helix, along the antenna's axis.

The radio equipment carried by competitors on a course must be capable of receiving the signal being transmitted by the five transmitters and useful for radio direction finding, including a radio receiver, attenuator, and directional antenna.

The Deep Space Network uses 35 m dishes at about 1 cm wavelengths.

This is because a troubled spacecraft may be forced to use less than its normal transmitter power, attitude control problems may preclude the use of high-gain antennas, and recovering every bit of telemetry is critical to assessing the health of the spacecraft and planning the recovery.

Antenna gain is often quoted with respect to a hypothetical antenna that radiates equally in all directions, an isotropic radiator.

In every direction, the power gain of an isotropic antenna is equal to the efficiency, and hence is always at most 1, though it can and ideally should exceed 1 for a directional antenna.

A directional antenna or beam antenna is an antenna which radiates or receives greater power in specific directions allowing increased performance and reduced interference from unwanted sources.

Directional antennas provide increased performance over dipole antennas—or omnidirectional antennas in general—when greater concentration of radiation in a certain direction is desired.

Most commonly referred to during space missions, these antennas are also in use all over Earth, most successfully in flat, open areas where there are no mountains to disrupt radiowaves.

Most commonly referred to during space missions, these antennas are also in use all over Earth, most successfully in flat, open areas where there are no mountains to disrupt radiowaves.

Low-gain antennas are often used in spacecraft as a backup to the high-gain antenna, which transmits a much narrower beam and is therefore susceptible to loss of signal.

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.

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

Due to reciprocity, these two effects are equal—an antenna that makes a transmitted signal 100 times stronger (compared to an isotropic radiator) will also capture 100 times as much energy as the isotropic antenna when used as a receiving antenna.

Antenna gain is often quoted with respect to a hypothetical antenna that radiates equally in all directions, an isotropic radiator. Due to reciprocity, these two effects are equal—an antenna that makes a transmitted signal 100 times stronger (compared to an isotropic radiator) will also capture 100 times as much energy as the isotropic antenna when used as a receiving antenna.