Phased array

phased array radarphased-arrayphased-array radarphased array antennaarrayantenna arrayselectronically scanned arrayantenna arrayarraysPAR
In antenna theory, a phased array usually means an electronically scanned array, a computer-controlled array of antennas which creates a beam of radio waves that can be electronically steered to point in different directions without moving the antennas.wikipedia
444 Related Articles

Active electronically scanned array

AESAactive phased arrayAESA radar
An active phased array or active electronically scanned array (AESA) is a phased array in which each antenna element has its own transmitter/receiver unit, all controlled by the computer.
An active electronically scanned array (AESA) is a type of phased array antenna, which is a computer-controlled array antenna in which the beam of radio waves can be electronically steered to point in different directions without moving the antenna.

Antenna (radio)

antennaantennasradio antenna
In antenna theory, a phased array usually means an electronically scanned array, a computer-controlled array of antennas which creates a beam of radio waves that can be electronically steered to point in different directions without moving the antennas.
A phased array consists of two or more simple antennas which are connected together through an electrical network.

Microwave

microwavesmicrowave radiationmicrowave tube
Since the array must consist of many small antennas (sometimes thousands) to achieve high gain, phased arrays are mainly practical at the high frequency end of the radio spectrum, in the UHF and microwave bands, in which the antenna elements are conveniently small.
Another directive antenna practical at microwave frequencies is the phased array, a computer-controlled array of antennas which produces a beam which can be electronically steered in different directions.

Antenna array

directional arrayplanar arrayarray
In antenna theory, a phased array usually means an electronically scanned array, a computer-controlled array of antennas which creates a beam of radio waves that can be electronically steered to point in different directions without moving the antennas.
Some antenna arrays (such as military phased array radars) are composed of thousands of individual antennas.

Conformal antenna

Conformal arrayconformal to the device shape
A conformal antenna is a phased array in which the individual antennas, instead of being arranged in a flat plane, are mounted on a curved surface.
Conformal antennas are a form of phased array antenna.

Phased array ultrasonics

phased array imagingphased arrayphased array transducers
The phased array principle is also used in acoustics, and phased arrays of acoustic transducers are used in medical ultrasound imaging scanners (phased array ultrasonics), oil and gas prospecting (reflection seismology), and military sonar systems.
Single-element (non-phased array) probes, known technically as monolithic probes, emit a beam in a fixed direction.

Medical ultrasound

ultrasoundultrasonographysonogram
The phased array principle is also used in acoustics, and phased arrays of acoustic transducers are used in medical ultrasound imaging scanners (phased array ultrasonics), oil and gas prospecting (reflection seismology), and military sonar systems.
Newer technology transducers use phased array techniques to enable the ultrasound machine to change the direction and depth of focus.

Karl Ferdinand Braun

BraunKarl BraunBraun, Karl Ferdinand
Phased array transmission was originally shown in 1905 by Nobel laureate Karl Ferdinand Braun who demonstrated enhanced transmission of radio waves in one direction.
Braun invented the phased array antenna in 1905.

Luis Walter Alvarez

Luis AlvarezLuisLuis W. Alvarez
During World War II, Nobel laureate Luis Alvarez used phased array transmission in a rapidly steerable radar system for "ground-controlled approach", a system to aid in the landing of aircraft.
In working on the Microwave Early Warning system (MEW), Alvarez invented a linear dipole array antenna that not only suppressed the unwanted side lobes of the radiation field, but also could be electronically scanned without the need for mechanical scanning.

Radar

radar stationradarsradar system
During World War II, Nobel laureate Luis Alvarez used phased array transmission in a rapidly steerable radar system for "ground-controlled approach", a system to aid in the landing of aircraft. Phased arrays were invented for use in military radar systems, to scan the radar beam quickly across the sky to detect planes and missiles.
Another method of steering is used in a phased array radar.

Fire-control radar

fire control radarradarfire control
Before using these systems, each surface-to-air missile in flight required a dedicated fire-control radar, which meant that radar-guided weapons could only engage a small number of simultaneous targets.
This works either by having the radar switch between sweeping the search sector and sending directed pulses at the target to be tracked, or by using a phased-array antenna to generate multiple simultaneous radar beams that both search and track.

X band

XX-bandX-
The antenna, which uses the X band, used 26 radiative elements and can gracefully degrade.
X band is used in radar applications including continuous-wave, pulsed, single-polarization, dual-polarization, synthetic aperture radar, and phased arrays.

Phased-array optics

phased arrayholographic display technologyoptical phased arrays
Within the visible or infrared spectrum of electromagnetic waves it is possible to construct optical phased arrays.
It is the optical analogue of phased array radar.

Multiplexing

multiplexedmultiplexmultiplexes
Synthetic array heterodyne detection is an efficient method for multiplexing an entire phased array onto a single element photodetector.
In wireless communications, multiplexing can also be accomplished through alternating polarization (horizontal/vertical or clockwise/counterclockwise) on each adjacent channel and satellite, or through phased multi-antenna array combined with a multiple-input multiple-output communications (MIMO) scheme.

Mammut radar

Mammut
At the same time, the GEMA in Germany built the Mammut 1.
It was the world's first phased array radar and was able to detect targets flying at an altitude of 8,000m at a range of 300km.

AN/SPS-48

SPS-48EAN/SPS-48ESPS-48C
This can be an advantage for communication links, and is used with the SPS-48 radar.
The AN/SPS-48 is a US naval electronically scanned array air search three-dimensional radar system manufactured by ITT Exelis and deployed in the 1960s as the primary air search sensor for anti-aircraft warships.

Passive electronically scanned array

PESAelectronically scannedelectronically steered
A passive phased array or passive electronically scanned array (PESA) is a phased array in which the antenna elements are connected to a single transmitter and/or receiver, as shown in the animation at top.
A passive electronically scanned array (PESA), also known as passive phased array, is a phased array antenna, that is an antenna in which the beam of radio waves can be electronically steered to point in different directions, in which all the antenna elements are connected to a single transmitter (such as a magnetron, a klystron or a travelling wave tube) and/or receiver.

History of smart antennas

History of smart antennas
Braun created a phased array by positioning three antennas to reinforce radiation in one direction and diminish radiation in other directions.

Side lobe

sidelobelobesidelobes
Other phasing adjustments can increase the downward radiation in the far field without tilting the main lobe, creating null fill to compensate for extremely high mountaintop locations, or decrease it in the near field, to prevent excessive exposure to those workers or even nearby homeowners on the ground.
For discrete aperture antennas (such as phased arrays) in which the element spacing is greater than a half wavelength, the spatial aliasing effect causes some sidelobes to become substantially larger in amplitude, and approaching the level of the main lobe; these are called grating lobes, and they are identical, or nearly identical in the example shown, copies of the main beams.

Beamforming

beam formingbeamformerAntenna beamforming
Beamforming
With narrow-band systems the time delay is equivalent to a "phase shift", so in this case the array of antennas, each one shifted a slightly different amount, is called a phased array.

Null fill

Other phasing adjustments can increase the downward radiation in the far field without tilting the main lobe, creating null fill to compensate for extremely high mountaintop locations, or decrease it in the near field, to prevent excessive exposure to those workers or even nearby homeowners on the ground.
This requires a phased array.

Thinned-array curse

thinned array cursesparse array
Thinned-array curse
It states that a transmitting antenna which is synthesized from a coherent phased array of smaller antenna apertures that are spaced apart will have a smaller minimum beam spot size (typically, the main lobe has a solid angle that is smaller by an amount proportional to the ratio of the area of the synthesized array to the total area of the individual apertures), but the amount of power that is beamed into this main lobe is reduced by an exactly proportional amount, so that the total power density in the beam is constant.

Inverse synthetic-aperture radar

inverse synthetic aperture radarinverse SARISAR
Inverse synthetic-aperture radar
This operation is equivalent to (but the inverse of) the generation of a large synthetic aperture phased array antenna formed by the coherent summation of the receiver outputs for varying target / antenna geometries.

Towed array sonar

towed arraytowed sonar arraytowfish
Phased arrays are used in naval sonar, in active (transmit and receive) and passive (receive only) and hull-mounted and towed array sonar.
Phased array

Active Phased Array Radar

APARThales APAR
The German Navy and the Royal Dutch Navy have developed the Active Phased Array Radar System (APAR).
Phased array