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| {{About|general theory and electromagnetic phased array|the ultrasonic and medical imaging application|phased array ultrasonics|the optical application|phased-array optics}}
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| [[Image:PAVE PAWS Radar Clear AFS Alaska.jpg|thumb|[[PAVE PAWS]] phased array radar in Alaska]]
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| [[File:Radar RAF Fylingdales.jpg|thumb|[[RAF Fylingdales]]]]
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| [[Image:Cobradane.jpg|thumb|[[Cobra Dane]]]]
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| [[File:PAVE PAWS&BMEWS.svg|thumb|BMEWS&[[PAVE PAWS]]]]
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| [[Image:Mammut Hoarding radar illustration.png|thumb|Mammut phased array radar [[World War II]]]]
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| In [[antenna (radio)|antenna]] theory, a '''phased array''' is an [[Antenna array (electromagnetic)|array of antennas]] in which the relative [[Phase (waves)|phases]] of the respective [[signaling (telecommunication)|signal]]s feeding the antennas are varied in such a way that the effective [[radiation pattern]] of the array is reinforced in a desired direction and suppressed in undesired directions.<ref>{{FS1037C MS188}} [http://glossary.its.bldrdoc.gov/fs-1037/dir-027/_3979.htm Definition of Phased Array]. Accessed April 27, 2006.</ref>
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| An [[antenna array]] is a group of multiple active antennas coupled to a common source or load to produce a directive radiation pattern. Usually, the spatial relationship of the individual antennas also contributes to the directivity of the antenna array. Use of the term "[[active antenna]]s" is intended to describe elements whose energy output is modified due to the presence of a source of energy in the element (other than the mere signal energy which passes through the circuit) or an element in which the energy output from a source of energy is controlled by the signal input. One common application of this is with a standard multiband [[television antenna]], which has multiple elements coupled together.
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| ==History==
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| Phased array transmission was originally developed in 1905 by [[Nobel Prize|Nobel]] Laureate [[Karl Ferdinand Braun]] who demonstrated enhanced transmission of [[radio]] waves in one direction.<ref>http://nobelprize.org/nobel_prizes/physics/laureates/1909/braun-lecture.pdf Braun's Nobel Prize lecture. The phased array section is on pages 239-240.</ref><ref>"Die Strassburger Versuche über gerichtete drahtlose Telegraphie" (The Strassburg experiments on directed wireless telegraphy), ''Elektrotechnische und Polytechnische Rundschau'' (Electrical technology and polytechnic review [a weekly]), (1 November 1905). This article is summarized (in German) in:
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| Adolf Prasch, ed., ''Die Fortschritte auf dem Gebiete der Drahtlosen Telegraphie'' [Progress in the field of wireless telegraphy] (Stuttgart, Germany: Ferdinand Enke, 1906), vol. 4, [http://books.google.com/books?id=ZAAMAAAAYAAJ&pg=RA1-PA184#v=onepage&q&f=false pages 184-185].</ref> During [[World War II]], [[Nobel Prize|Nobel]] Laureate [[Luis Walter Alvarez|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. At the same time, the GEMA in Germany built the PESA
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| [[Mammut radar|Mammut]] 1.<ref>http://www.100jahreradar.de/index.html?/gdr_5_deutschefunkmesstechnikim2wk.html Mamut1 first early warning PESA Radar</ref> It was later adapted for [[radio astronomy]] leading to [[Nobel Prize for Physics|Nobel Prizes for Physics]] for [[Antony Hewish]] and [[Martin Ryle]] after several large phased arrays were developed at the [[University of Cambridge]]. The design is also used in radar, and is generalized in [[interferometry|interferometric]] radio antennas. In 2007, [[DARPA]] researchers announced a 16 element phased array integrated with all necessary circuits to send at 30–50 GHz on a single silicon chip for military purposes.<ref>[http://ucsdnews.ucsd.edu/newsrel/science/10-07PhasedArrayChipDK-L.asp World’s Most Complex Silicon Phased Array Chip Developed at UC San Diego] in UCSD News (reviewed 02. November 2007)</ref>
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| ==Usage==
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| The relative [[amplitude]]s of — and constructive and destructive [[Interference (wave propagation)|interference]] effects among — the signals radiated by the individual antennas determine the effective [[radiation pattern]] of the array. A phased array may be used to point a fixed radiation pattern, or to [[wikt:scan|scan]] rapidly in [[azimuth]] or elevation. Simultaneous electrical scanning in both azimuth and elevation was first demonstrated in a phased array antenna at Hughes Aircraft Company, Culver City, California in 1957.<ref>See Joseph Spradley, “A Volumetric Electrically Scanned Two-Dimensional Microwave Antenna Array,” IRE National Convention Record, Part I - Antennas and Propagation; Microwaves, New York: The Institute of Radio Engineers, 1958, 204-212.</ref>
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| The phased array is used for instance in [[optical communication]] as a [[wavelength]]-selective [[demux|splitter]].
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| For information about active as well as passive phased array radars, see also [[active electronically scanned array]].
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| ===Broadcasting===
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| In [[broadcast engineering]], it is required that phased arrays be 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]]. More modest phased array longwire antenna systems may be employed by private radio enthusiasts to receive longwave, mediumwave (AM) and shortwave radio broadcasts from great distances.
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| On [[VHF]], phased arrays are used extensively for [[FM broadcasting]]. These greatly increase the [[antenna gain]], magnifying the emitted RF energy toward the [[horizon]], which in turn greatly increases a station's [[broadcast range]]. In these situations, the distance to each element from the transmitter is identical, or is one (or other [[integer]]) wavelength apart. Phasing the array such that the lower elements are slightly delayed (by making the distance to them longer) causes a downward [[beam tilt]], which is very useful if the antenna is quite high on a [[radio tower]].
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| Other phasing adjustments can increase the downward radiation in the [[far field]] without tilting the main [[Side lobe|lobe]], creating [[null fill]] to compensate for extremely high [[mountain]]top locations, or decrease it in the [[near and far field|near field]], to prevent excessive exposure to those workers or even nearby homeowners on the ground. The latter effect is also achieved by half-wave spacing – inserting additional elements halfway between existing elements with full-wave spacing. This phasing achieves roughly the same horizontal gain as the full-wave spacing; that is, a five-element full-wave-spaced array equals a nine- or ten-element half-wave-spaced array.
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| ===Naval usage===
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| <!-- Deleted image removed: [[Image:USSMasonDDG-87.jpg|thumb|upright|Port and starboard hexagonal panels are the phased array radar, AN/SPY-1D, on the [[USS Mason (DDG-87)|''USS Mason'' (DDG-87)]].]] -->
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| Phased array radar systems are also used by [[warships]] of many navies. Because of the rapidity with which the 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 ships 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 radar beam is 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. 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 | last = | first = | authorlink = http://www.janes.com/company/about/| coauthors = | title = AEGIS Weapon System MK-7| work = | publisher = [[Jane's Information Group]] | date = 2001-04-25| url = http://www.janes.com/defence/naval_forces/news/misc/aegis010425.shtml| doi = | accessdate = 2006-08-10 |archiveurl = http://web.archive.org/web/20060701055247/http://www.janes.com/defence/naval_forces/news/misc/aegis010425.shtml <!-- Bot retrieved archive --> |archivedate = 2006-07-01}}.</ref> Likewise, the [[Thales Group|Thales Herakles]] phased array multi-function radar on board the [[Formidable class frigate]]s of the [[Republic of Singapore Navy]] 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>
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| The [[German Navy]] and the [[Dutch Navy]] have developed the [[Active Phased Array Radar]] System (APAR).
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| [[Image:APAR.jpg|thumb|[[Active Phased Array Radar]] mounted on top of [[Sachsen class frigate]] F220 ''Hamburg's'' superstructure of the [[German Navy]].]]
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| :''See also: [[Active Electronically Scanned Array]], [[Aegis combat system]] and [[AN/SPY-1]]''
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| Phased arrays are used in naval sonar, in active (transmit and receive) and passive (receive only) and hull-mounted and [[towed array sonar]].
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| ===Space probe communication===
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| The [[MESSENGER]] spacecraft is a mission to the planet [[Mercury (planet)|Mercury]] (arrival 18 March 2011). This spacecraft is the first deep-space mission to use a phased-array antenna for [[telecommunication|communication]]s. The radiating elements are [[linear polarization|linearly-polarized]], slotted [[waveguide]]s. The antenna, which uses the [[X band]], uses 26 radiative elements but can gracefully downgrade.<ref>[http://www.jhuapl.edu/messenger/the_mission/publications/Wallis_Cheng.2001.pdf Phased-Array Antenna for the MESSENGER Deep Space Mission]</ref>
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| ===Weather research usage===
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| [[Image:Par installation.jpg|thumb|left|AN/SPY-1A radar installation at [[NSSL]], Norman, Oklahoma. The round dome primarily provides weather protection.]]
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| 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 [http://www.bcisse.com/ 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]. Accessed April 6, 2006.</ref>
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| ===Optics===
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| 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], ''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.
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| ===Radio-frequency identification (RFID)===
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| Recently, phased array antennas have been included in [[RFID]] systems to significantly boost the reading capability of passive [[UHF]] tags passing from 30 feet to 600 feet.<ref>[http://www.rfidradio.com/?p=25 RFID Radio]{{broken link|date=January 2014}}</ref>
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| ===Human-machine interfaces (HMI)===
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| A phased array of acoustic transducers, denominated airborne ultrasound tactile display (AUTD), was developed at the University of Tokyo's Shinoda Lab to induce tactile feedback.<ref><cite web |archiveurl=http://web.archive.org/web/20090318064419/http://www.alab.t.u-tokyo.ac.jp/~siggraph/08/Tactile/SIGGRAPH08-Tactile.html|archivedate=March 18, 2009|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>[http://www.alab.t.u-tokyo.ac.jp/~siggraph/09/TouchableHolography/SIGGRAPH09-TH.html] SIGGRAPH 2009, Touchable holography</ref>
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| ==Mathematical perspective and formulas==
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| A phased array is an example of ''N''-slit [[diffraction]]. It may also be viewed as the coherent addition of ''N'' [[line source]]s. Since each individual antenna acts as a slit, emitting radio waves, their diffraction pattern can be calculated by adding the phase shift φ to the fringing term.
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| We will begin from the ''N''-slit diffraction pattern derived on the [[diffraction formalism]] page.
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| :<math>\psi ={{\psi }_0}\left(\frac{\sin \left(\frac{{\pi a}}{\lambda }\sin\theta \right)}{\frac{{\pi a}}{\lambda }\sin\theta}\right)\left(\frac{\sin
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| \left(\frac{N}{2}{kd}\sin\theta\right)}{\sin \left(\frac{{kd}}{2}\sin\theta \right)}\right)
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| </math>
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| Now, adding a φ term to the <math>\begin{matrix}kd\sin\theta\,\end{matrix}</math> fringe effect in the second term yields:
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| :<math>\psi ={{\psi }_0}\left(\frac{\sin \left(\frac{{\pi a}}{\lambda }\sin \theta\right)}{\frac{{\pi a}}{\lambda }\sin\theta}\right)\left(\frac{\sin
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| \left(\frac{N}{2}\big(\frac{{2\pi d}}{\lambda }\sin\theta + \phi \big)\right)}{\sin \left(\frac{{\pi d}}{\lambda }\sin\theta +\phi \right)}\right)
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| </math>
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| Taking the square of the wave function gives us the intensity of the wave.
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| :<math>I = I_0{{\left(\frac{\sin \left(\frac{\pi a}{\lambda }\sin\theta\right)}{\frac{{\pi a}}{\lambda } \sin \theta
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| }\right)}^2}{{\left(\frac{\sin \left(\frac{N}{2}(\frac{2\pi d}{\lambda} \sin\theta+\phi )\right)}{\sin \left(\frac{{\pi d}}{\lambda
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| } \sin\theta+\phi \right)}\right)}^2}
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| </math>
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| :<math>
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| I =I_0{{\left(\frac{\sin \left(\frac{{\pi a}}{\lambda } \sin\theta\right)}{\frac{{\pi a}}{\lambda }
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| \sin\theta}\right)}^2}{{\left(\frac{\sin \left(\frac{\pi }{\lambda } N d \sin\theta+\frac{N}{2} \phi \right)}{\sin
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| \left(\frac{{\pi d}}{\lambda } \sin\theta+\phi \right)}\right)}^2}
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| </math>
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| Now space the emitters a distance <math> d=\begin{matrix}\frac{\lambda}{4}\end{matrix}</math> apart. This distance is chosen for simplicity of calculation but can be adjusted as any scalar fraction of the wavelength.
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| :<math>I =I_0{{\left(\frac{\sin \left(\frac{\pi a}{\lambda } \sin\theta \right)}{\frac{\pi a}{\lambda }
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| \sin\theta }\right)}^2}{{\left(\frac{\sin \left(\frac{\pi }{4} N \sin\theta+\frac{N}{2} \phi \right)}{\sin \left(\frac{\pi }{4}
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| \sin\theta+ \phi \right)}\right)}^2}</math>
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| As sine achieves its maximum at <math>\begin{matrix}\frac{\pi}{2}\end{matrix}</math>, we set the numerator of the second term = 1.
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| :<math>
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| \frac{\pi }{4} N \sin\theta+\frac{N}{2} \phi = \frac{\pi }{2}
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| </math>
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| :<math>
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| \sin\theta=\left(\frac{\pi }{2} - \frac{N}{2} \phi \right)\frac{4}{N \pi }
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| </math>
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| :<math>
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| \sin\theta=\frac{2}{N}-\frac{2\phi }{\pi }
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| </math>
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| Thus as ''N'' gets large, the term will be dominated by the <math>\begin{matrix}\frac{2\phi}{\pi}\end{matrix}</math> term. As sine can oscillate between −1 and 1, we can see that setting <math>\phi=-\begin{matrix}\frac{\pi}{2}\end{matrix}</math> will send the maximum energy on an angle given by
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| :<math>\theta = \sin^{-1}(1) = \begin{matrix}\frac{\pi}{2}\end{matrix} = 90^{\circ}</math>
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| Additionally, we can see that if we wish to adjust the angle at which the maximum energy is emitted, we need only to adjust the phase shift φ between successive antennas. Indeed the phase shift corresponds to the negative angle of maximum signal.
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| A similar calculation will show that the denominator is minimized by the same factor.
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| == Different types of phased arrays ==
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| {{main|Beamforming}}
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| {{move portions to|Beamforming|date=September 2013}}
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| There are two main types of beamformers. These are [[time domain]] beamformers and [[frequency domain]] beamformers.
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| A graduated attenuation window is sometimes applied across the face of the array to improve side-lobe suppression performance, in addition to the phase shift.
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| Time domain beamformer works by introducing time delays. The basic operation is called "delay and sum". It delays the incoming signal from each array element by a certain amount of time, and then adds them together. The most common kind of time domain beam former is serpentine waveguide. Active phase array uses individual delay lines that are switched on and off. [[Yttrium iron garnet]] phase shifters vary the phase delay using the strength of a magnetic field.
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| There are two different types of frequency domain beamformers.
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| The first type separates the different frequency components that are present in the received signal into multiple frequency bins (using either an [[Discrete Fourier transform]] (DFT) or a [[filterbank]]). When different delay and sum beamformers are applied to each frequency bin, the result is that the main lobe simultaneously points in multiple different directions at each of the different frequencies. This can be an advantage for communication links, and is used with the [[SPS-48]] radar.
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| The other type of frequency domain beamformer makes use of Spatial Frequency. Discrete samples are taken from each of the individual array elements. The samples are processes using a [[Discrete Fourier Transform]] (DFT). The DFT introduces multiple different discrete phase shifts during processing. The outputs of the DFT are individual channels that correspond with evenly spaced beams formed simultaneously. A 1 dimensional DFT produces a fan of different beams. A 2 dimensional DFT produces beams with a [[pineapple]] configuration.
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| These techniques are used to create two kinds of phase array.
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| :* Dynamic - an array of variable phase shifters are used to move the beam
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| :* Fixed - the beam position is stationary with respect to the array face and the whole antenna is moved
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| There are two further sub-categories that modify the kind of dynamic array or fixed array.
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| :* Active - amplifiers or processors in each phase shifter element
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| :* Passive - large central amplifier with attenuating phase shifters
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| ===Dynamic Phased Array===
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| Each array element incorporates an adjustable phase shifter that are collectively used to move the beam with respect to the array face.
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| Dynamic phase array require no physical movement to aim the beam. The beam is moved electronically. This can produce antenna motion fast enough to use a small pencil-beam to simultaneously track multiple targets while searching for new targets using just one radar set (track while search).
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| As an example, an antenna with a 2 degree beam with a pulse rate of 1 kHz will require approximately 16 seconds to cover an entire a hemisphere consisting of 16,000 pointing positions. This configuration provides 6 opportunities to detect a Mach 3 vehicle over a range of {{convert|100|km|mi|abbr=on}}, which is suitable for military applications.
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| The position of mechanically steered antennas can be predicted, which can be used to create [[electronic countermeasures]] that interfere with radar operation. The flexibility resulting from phase array operation allows beams to be aimed at random locations, which eliminates this vulnerability. This is also desirable for military applications.
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| ===Fixed Phase Array===
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| Fixed phase array antennas are typically used to create an antenna with a more desirable form factor than the conventional [[parabolic reflector]] or [[cassegrain reflector]]. Fixed phased array radar incorporate fixed phase shifters. This kind of phase array is physically moved during the track and scan process. There are two configurations.
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| :* Multiple frequencies with a delay-line | |
| :* Multiple adjacent beams
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| The [[SPS-48]] radar uses multiple transmit frequencies with a serpentine delay line along the left side of the array to produce vertical fan of stacked beams. Each frequency experiences a different phase shift as it propagates down the serpentine delay line, which forms different beams. A filter bank is used to split apart the individual receive beams. The antenna is mechanically rotated.
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| [[Semi-active radar homing]] uses [[monopulse radar]] that relies on a fixed phase array to produce multiple adjacent beams that measure angle errors. This form factor is suitable for [[gimbal]] mounting in missile seekers.
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| ===Active Phase Array===
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| Active phase arrays elements incorporate transmit amplification with phase shift in each antenna element (or group of elements). Each element also includes receive pre-amplification. The phase shifter setting is the same for transmit and receive.
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| Active phase array do not require phase reset after the end of the transmit pulse, which is compatible with [[Doppler radar]] and [[Pulse-Doppler radar]].
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| ===Passive Phase Array===
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| Passive phase arrays typically use large amplifiers that produce all of the microwave transmit signal for the antenna. Phase shifters typically consist of waveguide elements that contain phase shifters controlled by magnetic field, voltage gradient, or equivalent technology.<ref>{{cite web|url=http://scholarworks.sjsu.edu/cgi/viewcontent.cgi?article=5082&context=etd_theses&sei-redir=1&referer=http%3A%2F%2Fwww.google.com|title=YIG-sphere-based phase shifter for X-band phased array applications|publisher=Scholarworks}}</ref><ref>{{cite web|url=http://www.microwaves101.com/encyclopedia/phaseshifters_ferro.cfm|title=Ferroelectric Phase Shifters|publisher=Microwaves 101}}</ref>
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| The phase shift process used with passive phase array typically puts the receive beam and transmit beam into caddy-corner quadrants. The sign of the phase shift must be inverted after the transmit pulse is finished and before the receive period begins to place the receive beam into the same location as the transmit beam. That requires a phase impulse that degrades sub-clutter visibility performance on [[Doppler radar]] and [[Pulse-Doppler radar]]. As an example, [[Yttrium iron garnet]] phase shifters must be changed after transmit pulse quench and before receiver processing starts to align transmit and receive beams. That impulse introduces FM noise that degrades clutter performance.
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| Passive phase array is used with AEGIS.<ref>{{cite web|url=http://www.dtic.mil/dtic/tr/fulltext/u2/a460426.pdf|title=Total Ownership Cost Reduction Case Study: AEGIS Radar Phase Shifters|publisher=Naval Postgraduate School}}</ref>
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| == See also ==
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| * [[Active Electronically Scanned Array]]
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| * [[Active Phased Array Radar]]
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| * [[Antenna array (electromagnetic)]]
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| * [[Aperture synthesis]]
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| * [[Beamforming]]
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| * [[Interferometric synthetic aperture radar]]
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| * [[Inverse synthetic aperture radar]] (ISAR)
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| * [[Optical heterodyne detection]]
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| * [[Phased array ultrasonics]]
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| * [[Phased-array optics]]
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| * [[Radar MASINT]]
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| * [[Rajendra Radar]], [[India]]
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| * [[Side-scan sonar]]
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| * [[Single frequency network]]
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| * [[Smart antenna]]
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| * [[Synthetic aperture radar]]
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| * [[Synthetic aperture sonar]]
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| * [[Synthetically thinned aperture radar]]
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| * [[Thinned array curse]]
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| * [[Tikhomirov Scientific Research Institute of Instrument Design]] (NIIP) and [[Phazotron]] (NIIR), [[Russia]]n developers of phased arrays
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| * [[Wave field synthesis]]
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| * [[History of smart antennas]]
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| ==References==
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| {{Refbegin}}
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| {{Refend}}
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| {{Reflist}}
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| ==External links==
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| {{Commons category|Phased arrays}}
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| *[http://www.nssl.noaa.gov/par/ Radar Research and Development - Phased Array Radar] — [[National Severe Storms Laboratory]]
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| *[http://www.harpoonhq.com/waypoint/articles/Article_044.pdf Shipboard Phased Array Radars]
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| *[http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19870018450_1987018450.pdf NASA Report: MMICs For Multiple Scanning Beam Antennas for Space Applications]
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| *[http://www.radartutorial.eu/06.antennas/an14.en.html Principle of Phased Array] @ www.radartutorial.eu
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| *[http://www.sengpielaudio.com/TonyFaulknerPhasedArray06.htm 'Phased Array' microphone system of Tony Faulkner]
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| {{Antenna Types}}
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| {{DEFAULTSORT:Phased Array}}
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| [[Category:Broadcast engineering]]
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| [[Category:Domes]]
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| [[Category:Radar]]
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| [[Category:Radio frequency antenna types]]
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| [[Category:Wireless locating]]
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