Editing Phased array (section)

== Applications ==

=== Radar ===
Phased arrays were invented for radar tracking of ballistic missiles, and because of their fast tracking abilities phased array radars are widely used in military applications.  For example, because of the rapidity with which the [[Beam steering|beam can be steered]], phased array radars allow a warship to use one [[radar]] system for surface detection and tracking (finding ships), air detection and tracking (finding aircraft and missiles) and missile uplink capabilities. 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. Phased array systems can be used to control missiles during the mid-course phase of the missile's flight. During the terminal portion of the flight, [[continuous-wave]] fire control directors provide the final guidance to the target. Because the antenna pattern is [[Beam steering|electronically steered]], phased array systems can direct radar beams fast enough to maintain a [[fire-control system|fire control quality]] track on many targets simultaneously while also controlling several in-flight missiles.

[[File:APAR.jpg|thumb|[[Active Phased Array Radar]] mounted on top of [[Sachsen-class frigate|''Sachsen''-class frigate]] F220 ''Hamburg's'' superstructure of the [[German Navy]]]]
The [[AN/SPY-1]] phased array radar, part of the [[Aegis Combat System]] deployed on modern U.S. [[cruisers]] and [[destroyers]], "is able to perform search, track and missile guidance functions simultaneously with a capability of over 100 targets."<ref>{{cite web|title=AEGIS Weapon System MK-7 |publisher=[[Jane's Information Group]] |date=2001-04-25 |url=http://www.janes.com/defence/naval_forces/news/misc/aegis010425.shtml |access-date=10 August 2006 |archive-url=https://web.archive.org/web/20060701055247/http://www.janes.com/defence/naval_forces/news/misc/aegis010425.shtml |archive-date=1 July 2006 |url-status=dead }}.</ref> Likewise, the [[Thales Herakles]] phased array multi-function radar used in service with [[France]] and [[Singapore]] has a track capacity of 200 targets and is able to achieve automatic target detection, confirmation and track initiation in a single scan, while simultaneously providing mid-course guidance updates to the [[MBDA Aster]] missiles launched from the ship.<ref>{{cite journal |last=Scott |first=Richard |date=April 2006 |title=Singapore Moves to Realise Its Formidable Ambitions|journal=Jane's Navy International |volume=111 |issue=4 |pages=42–49}}</ref> The [[German Navy]] and the [[Royal Dutch Navy]] have developed the [[Active Phased Array Radar]] System (APAR). The [[MIM-104 Patriot]] and other ground-based antiaircraft systems use phased array radar for similar benefits.

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

{{See also |SAMPSON |Active Phased Array Radar |SMART-L |Active Electronically Scanned Array |Aegis combat system |AN/SPY-1 |Passive electronically scanned array }}

=== Space probe communication ===
The ''[[MESSENGER]]'' spacecraft was a [[space probe]] mission to the planet [[Mercury (planet)|Mercury]] (2011–2015<ref name=nyt20150430>{{cite news |last=Corum |first=Jonathan |title=Messenger's Collision Course With Mercury |url=https://www.nytimes.com/interactive/2015/04/30/science/space/messenger-collides-with-mercury.html |date=April 30, 2015 |work=[[New York Times]] |access-date=10 May 2015 |url-status=live |archive-url=https://web.archive.org/web/20150510040355/http://www.nytimes.com/interactive/2015/04/30/science/space/messenger-collides-with-mercury.html |archive-date=10 May 2015 }}</ref>). This was the first deep-space mission to use a phased-array antenna for [[telecommunications|communications]]. The radiating elements are [[circular polarization|circularly-polarized]], slotted [[waveguide]]s. The antenna, which uses the [[X band]], used 26 radiative elements and can [[Fault tolerance|gracefully degrade]].<ref>{{cite web|url=http://messenger.jhuapl.edu/the_mission/publications/Wallis_Cheng.2001.pdf |title=Phased-Array Antenna System for the MESSENGER Deep Space Mission |last1=Wallis |first1=Robert E. |last2=Cheng |first2=Sheng |publisher=[[Johns Hopkins University Applied Physics Laboratory]] |access-date=11 May 2015 |archive-url=https://web.archive.org/web/20150518091704/http://messenger.jhuapl.edu/the_mission/publications/Wallis_Cheng.2001.pdf |archive-date=18 May 2015 |url-status=dead }}</ref>

=== Weather research usage ===
[[File:Par installation.jpg|thumb|left|AN/SPY-1A  radar installation at [[National Severe Storms Laboratory]], Norman, Oklahoma. The enclosing [[radome]] provides weather protection.]]
The [[National Severe Storms Laboratory]] has been using a SPY-1A phased array antenna, provided by the US Navy, for weather research at its [[Norman, Oklahoma]] facility since April 23, 2003. It is hoped that research will lead to a better understanding of thunderstorms and tornadoes, eventually leading to increased warning times and enhanced prediction of tornadoes. Current project participants include the National Severe Storms Laboratory and National Weather Service Radar Operations Center, [[Lockheed Martin]], [[United States Navy]], [[University of Oklahoma]] School of Meteorology, School of Electrical and Computer Engineering, and [[Atmospheric Radar Research Center]], Oklahoma State Regents for Higher Education, the [[Federal Aviation Administration]], and Basic Commerce and Industries. The project includes [[research and development]], future [[technology transfer]] and potential deployment of the system throughout the United States. It is expected to take 10 to 15 years to complete and initial construction was approximately $25 million.<ref>[[National Oceanic and Atmospheric Administration]]. [http://www.norman.noaa.gov/publicaffairs/backgrounders/backgrounder_par.html PAR Backgrounder] {{webarchive|url=https://web.archive.org/web/20060509134036/http://www.norman.noaa.gov/publicaffairs/backgrounders/backgrounder_par.html |date=2006-05-09 }}. Accessed 6 April 2006.</ref> A team from Japan's RIKEN Advanced Institute for Computational Science (AICS) has begun experimental work on using phased-array radar with a new algorithm for [[3D NowCasting|instant weather forecasts]].<ref>{{cite journal|last1=Otsuka|first1=Shigenori|last2=Tuerhong|first2=Gulanbaier|last3=Kikuchi|first3=Ryota|last4=Kitano|first4=Yoshikazu|last5=Taniguchi|first5=Yusuke|last6=Ruiz|first6=Juan Jose|last7=Satoh|first7=Shinsuke|last8=Ushio|first8=Tomoo|last9=Miyoshi|first9=Takemasa|title=Precipitation Nowcasting with Three-Dimensional Space–Time Extrapolation of Dense and Frequent Phased-Array Weather Radar Observations|journal=Weather and Forecasting|date=February 2016|volume=31|issue=1|pages=329–340|doi=10.1175/WAF-D-15-0063.1|bibcode=2016WtFor..31..329O}}</ref>

=== Optics ===
{{Main|Phased-array optics}}
Within the visible or infrared spectrum of electromagnetic waves it is possible to construct [[phased-array optics|optical phased arrays]]. They are used in wavelength multiplexers and filters for telecommunication purposes,<ref>P. D. Trinh, S. Yegnanarayanan, F. Coppinger and B. Jalali [http://www.ee.ucla.edu/~oecs/comp_pub/intr_opt/Optics23.pdf Silicon-on-Insulator (SOI) Phased-Array Wavelength Multi/Demultiplexer with Extremely Low-Polarization Sensitivity] {{webarchive|url=https://web.archive.org/web/20051208105830/http://www.ee.ucla.edu/~oecs/comp_pub/intr_opt/Optics23.pdf |date=2005-12-08 }}, ''IEEE Photonics Technology Letters'', Vol. 9, No. 7, July 1997</ref> laser [[beam steering]], and holography. [[Synthetic array heterodyne detection]] is an efficient method for [[multiplexing]] an entire phased array onto a single element [[photodetector]]. The dynamic beam forming in an optical phased array transmitter can be used to electronically raster or vector scan images without using lenses or mechanically moving parts in a lensless projector.<ref name=":0">{{Cite web|url=http://authors.library.caltech.edu/60779/1/06886570.pdf|title=Electronic Two-Dimensional Beam Steering for Integrated Optical Phased Arrays|archive-url=https://web.archive.org/web/20170809130907/http://authors.library.caltech.edu/60779/1/06886570.pdf|archive-date=2017-08-09|url-status=live}}</ref> Optical phased array receivers have been demonstrated to be able to act as lensless cameras by selectively looking at different directions.<ref name=":1">{{Cite web|url=http://chic.caltech.edu/wp-content/uploads/2017/03/Cleo_2017_2D_OPA_V7.pdf|title=An 8x8 Heterodyne Lens-less OPA Camera|archive-url=https://web.archive.org/web/20170713050602/http://chic.caltech.edu/wp-content/uploads/2017/03/Cleo_2017_2D_OPA_V7.pdf|archive-date=2017-07-13|url-status=live}}</ref><ref name=":2">{{Cite web|url=http://chic.caltech.edu/wp-content/uploads/2016/06/CLEO_SI-2016-STu3G.3.pdf|title=A One-Dimensional Heterodyne Lens-Free OPA Camera|archive-url=https://web.archive.org/web/20170722055717/http://chic.caltech.edu/wp-content/uploads/2016/06/CLEO_SI-2016-STu3G.3.pdf|archive-date=2017-07-22|url-status=live}}</ref>

=== Satellite broadband internet transceivers ===
[[Starlink]] is a [[low Earth orbit]] [[satellite constellation]] that is available in over a hundred countries. It provides broadband internet connectivity to consumers; the user terminals of the system use phased array antennas.<ref>
{{cite AV media |people=Elon Musk, Mike Suffradini |date=7 July 2015 |title=ISSRDC 2015{{Snd}} A Conversation with Elon Musk (2015.7.7) |medium=video |url=https://www.youtube.com/watch?v=ZmEg95wPiVU |access-date=2015-12-30 |time=46:45–50:40 }}</ref>

=== Radio-frequency identification (RFID) ===
By 2014, phased array antennas were integrated into [[RFID]] systems to increase the area of coverage of a single system by 100% to {{convert|76200|sqm|sqft|abbr=on}} while still using traditional passive [[UHF]] tags.<ref>{{cite web |url=http://www.mojix.com/pdf/Mojix_STAR_System.pdf |title=Mojix Star System |access-date=24 October 2014 |url-status=dead |archive-url=https://web.archive.org/web/20110516020744/http://www.mojix.com/pdf/Mojix_STAR_System.pdf |archive-date=16 May 2011 }}</ref>

=== Human-machine interfaces (HMI) ===
A phased array of acoustic transducers, denominated airborne ultrasound tactile display (AUTD), was developed in 2008 at the University of Tokyo's Shinoda Lab to induce tactile feedback.<ref>{{cite web |archive-url=https://web.archive.org/web/20090318064419/http://www.alab.t.u-tokyo.ac.jp/~siggraph/08/Tactile/SIGGRAPH08-Tactile.html |archive-date=18 March 2009|title=Airborne Ultrasound Tactile Display|url=http://www.alab.t.u-tokyo.ac.jp/~siggraph/08/Tactile/SIGGRAPH08-Tactile.html}} SIGGRAPH 2008, Airborne Ultrasound Tactile Display</ref> This system was demonstrated to enable a user to interactively manipulate virtual holographic objects.<ref>{{cite web|url=http://www.alab.t.u-tokyo.ac.jp/~siggraph/09/TouchableHolography/SIGGRAPH09-TH.html |title=Touchable Holography |access-date=2009-08-22 |url-status=dead |archive-url=https://web.archive.org/web/20090831054307/http://www.alab.t.u-tokyo.ac.jp/~siggraph/09/TouchableHolography/SIGGRAPH09-TH.html |archive-date=2009-08-31 }} SIGGRAPH 2009, Touchable holography</ref>

=== Radio astronomy ===
Phased Array Feeds (PAF)<ref>{{Cite journal|last1=Hay|first1=S.G.|last2=O’Sullivan|first2=J.D.|date=2008|title=Analysis of common-mode effects in a dual-polarized planar connected-array antenna|journal=Radio Science|volume=43|issue=6|pages=RS6S04|doi=10.1029/2007RS003798|bibcode=2008RaSc...43.6S04H|doi-access=free}}</ref> have recently been used at the focus of [[radio telescope]]s to provide many beams, giving the radio telescope a very wide [[Angle of view|field of view]]. Three examples are the [[Australian Square Kilometre Array Pathfinder|ASKAP]] telescope in [[Australia]], the Apertif upgrade to the [[Westerbork Synthesis Radio Telescope]] in The [[Netherlands]], and the Florida Space Institute in the United States .

=== Broadcasting ===
In [[broadcast engineering]], the term 'phased array' has a meaning different from its normal meaning, it means an ordinary [[array antenna]], an array of multiple [[mast radiator]]s designed to radiate a [[directional antenna|directional]] radiation pattern, as opposed to a single mast which radiates an [[omnidirectional antenna|omnidirectional]] pattern. Broadcast phased arrays have fixed radiation patterns and are not 'steered' during operation as are other phased arrays.

Phased arrays are used by many [[AM broadcasting|AM broadcast]] [[radio stations]] to enhance [[signal strength]] and therefore coverage in the [[city of license]], while minimizing [[Interference (communication)|interference]] to other areas. Due to the differences between daytime and nighttime [[ionosphere|ionospheric]] [[radio propagation|propagation]] at [[mediumwave]] frequencies, it is common for AM broadcast stations to change between day ([[groundwave]]) and night ([[skywave]]) radiation patterns by switching the [[phase (waves)|phase]] and power levels supplied to the individual antenna elements ([[mast radiator]]s) daily at [[sunrise]] and [[sunset]]. For [[shortwave]] broadcasts many stations use arrays of horizontal dipoles. A common arrangement uses 16 dipoles in a 4×4 array. Usually this is in front of a wire grid reflector. The phasing is often switchable to allow [[beam steering]] in azimuth and sometimes elevation.