Phased-array - Factbites

Phased-array - Factbites
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Topic: Phased-array

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	Phased array - Wikipedia, the free encyclopedia
		In telecommunication, a phased array is a group of antennas in which the relative phases of the respective signals 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.
		Phased arrays are required to be used by many AM broadcast stations to enhance signal coverage in the city of license, while minimizing interference to other areas.
		A phased array may be used to point a fixed radiation pattern, or to scan rapidly in azimuth or elevation.
	en.wikipedia.org /wiki/Phased_array (741 words)

	MEASUREMENT OF THE EARTH-OBSERVER-1 SATELLITE X-BAND PHASED ARRAY
		The phased array was installed on the spacecraft and near-field testing was repeated during the spacecraft integration, figure 1.
		The phased array with its embedded active amplifiers was measured for output power versus input power to determine the compression level of the active amplifiers behind each antenna element.
		Since the phased array has no method for RF monitoring of all of the distributed amplifiers behind each phased array antenna element, the health of the phased array package can be monitored as needed.
	www.nearfield.com /amta/AMTA03_Swales_JND.htm (2135 words)

	BBC - h2g2 - Phased Array Antennae - A743799
		The term 'phased array' originates from the fact that when considering sinusoidal signals such as electromagnetic waves, time delay can be translated as a shift of the phase of the signal.
		Arrays and single feed antennae produce a beam which can only be moved in space by either moving the reflector, the feeder or the whole construction.
		In order to understand how an array antenna works, the basic wave superposition principle which was outlined in the entry about Antennae must be applied twice: the radiating elements can be thought of as consisting of radiation sources whose contributions are added in order to yield the directional pattern of the device.
	www.bbc.co.uk /dna/h2g2/alabaster/A743799 (1087 words)

	Phased Array Antenna
		Phased array antennas have low visibility, the difficulty to detect due to the fact that there are no moving parts.
		Having so many advantages over a single antenna, phased array antennas are widely used in both civilian operations, such as in air traffic, smart antennas, and broadcast satellite communications, and military areas, such as in marine radar, airborne radar, missile guidance, trajectory determination, and satellite communications.
		Phased array antennas have the character of quick steering, either electrical or optical controlled.
	www.mrc.utexas.edu /Chen/optic-inter/Phased_Array_Antenna.htm (795 words)

	Phased-Array Simulation For Antenna Test Range Design
		The approach taken is to simulate near-field data for a phased array antenna and to introduce specific mechanical and electrical inaccuracies and to study the impact that these will have on the far-field measurement result through comparison to the perfect case (no introduced inaccuracies).
		For the array, a Taylor aperture distribution is assumed in the horizontal direction and a constant distribution in the vertical direction.
		The near-field scan is simulated for a probe at a distance of 0.1m away from the array face and covering a scan area of 1.9m x 1.9m to allow far-field angular coverage from –80 to +80 degrees in both azimuth and elevation.
	www.nearfield.com /amta/Amta98_djr.htm (1752 words)

	Definition: phased array
		phased array: A group of antennas in which the relative phases of the respective signals 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.
		Note 2: A phased array may be used to point a fixed radiation pattern, or to scan rapidly in azimuth or elevation.
		(188) Note 1: The relative amplitudes of--and constructive and destructive interference effects among--the signals radiated by the individual antennas determine the effective radiation pattern of the array.
	glossary.its.bldrdoc.gov /fs-1037/dir-027/_3979.htm (107 words)

	Phased arrays and Jan C Somer
		In the phased-array system, all the elements of an array were used for each interrogation pulse and variable time delays were introduced between the various elements, both on transmission and reception, in such a way that effective launching and reception of an acoustic wave occurred predominantly in one defined direction.
		Similar to linear array designs, focusing in the direction at right angles to the scan plane determines the slice thickness and is accomplished by use of accoustic lens.
		Grating lobes are unique to array transducers and are caused by the regular, periodic spacing of the small array elements.
	www.ob-ultrasound.net /somers.html (1472 words)

	Project SPAS
		Phased arrays sytstems are highly useful in applications demanding a narrow beam that can be electronically adjusted to track moving targets, such as RADAR systems, mobile point-to-point communications systems, and communication with satellites.
		Phased arrays are a class of antenna arrays that can be electronically scanned to form a transmit or receive beam in a specific direction.
		For a phased array to accurate form a beam in a given direction, the phases and amplitudes required to form such a beam must be known beforehand so that they can be programmed into the array.
	www.enel.ucalgary.ca /~michal/ENEL619-50/Projects2003/SPAS/Project_SPAS.html (409 words)

	array.htm
		The technique of connecting mismatched feeders to the driven elements in a phased array is an expedient method for obtaining relative current phases in the elements that approximate the desired currents.
		However, it is important to realize that self-impedance is not determined by de-tuning the other elements in the array in order to obtain an omni-directional pattern.
		We would expect the relative phase in the first case to be less than it is in the second case, since the difference in physical line lengths is 6 inches in the first case and 20 inches in the second.
	www.qsl.net /km5kg/array.htm (7955 words)

	PHASED ARRAY ANTENNAS FOR SATELLITE TV
		The phased array antenna is characterized by its inherent high speed of beam switching and this enables one to use it in DBS systems to be installed on movable objects such as coaches, trucks and ships.
		The phased array antenna that uses a printed-circuit board as a radiating curtain and p-i-n diode based microstrip phase shifters appear to have considerable promise for meeting the challenge.
		The phased array use will permit user-friendly modes of operation, such as automatic search of satellites followed by memorizing their coordinates in order to switch over to the desired satellite within microseconds.
	brown.nord.nw.ru /ascor/ascor.htm (697 words)

	Phased Arrays for Networks
		Phased arrays of printed antennas are of considerable current interest, particularly in the context of millimeter-wave monolithic arrays, where active devices for phase shifters and amplifiers are integrated on the same or similar substrate as the radiating elements.
		In the WLAN application, another important advantage of phased arrays is that with its adaptive beam forming, users can find each other in a more efficient way while less power is consumed.
		To realize this reliable peer-to-peer approach, which allows direct communication between terminals without requiring a central base station, a phased array is used in the system front end.
	www.cco.caltech.edu /~mmic/reshpubindex/dai.html (338 words)

	Phased array element for multiband, multifunction apertures
		The resulting phased array antenna can be scanned to form a narrow, high gain beam in any direction within a scan cone.
		It provides more than one octave (67%) of bandwidth with scan, which is very wideband for a phased array; this performance had previously only been possible with much more expensive and thicker arrays.
		This phased array antenna can be used for multiband, multifunction ultra-wide band apertures.
	www.magneticsciences.com /PhasedArray.html (270 words)

	New Scientist Breaking News - Vast array of tiny antennas could talk to spacecraft
		The basic component of the array would be a square "tile" 25 centimetres to a side, consisting of a 10 by 10 grid of printed antennas on a circuit board, with a computer chip in the centre.
		The proposal is to build an array of millions of small antennas printed on circuit boards, just like the antennas in consumer electronics such as wireless headsets and GPS receivers.
		This will add about $50 per tile, or $25 million for a 500,000-tile array.
	www.newscientist.com /article.ns?id=dn8213&feedId=online-news_rss20 (599 words)

	Amazon.com: Phased Array Antennas (Wiley Series in Microwave and Optical Engineering): Books: R. C. Hansen
		Phased array antennas have many important applications, including radar uses in airport surveillance and missile detection and tracking, as well as applications in personal communication systems and in satellite communications.
		The first complete guide to phased array design and theory in more than thirty yearsandmdash;destined to become the standard reference in the field well into the twenty-first century The past twenty years have witnessed significant breakthroughs in our understanding of the principles behind phased array antennas and in their design and application.
		Phased Array Antennas is geared to the interests of both the practicing design engineer and the antenna array analyst.
	www.amazon.com /exec/obidos/tg/detail/-/047153076X?v=glance (1029 words)

	New Radar Technology Can Increase Tornado Warning Lead Times
		Phased array radar technology may help forecasters of the future provide earlier warnings for tornadoes and other types of severe and hazardous weather.
		Early tests of the phased array radar system show that the technology has the potential to vastly improve upon the capabilities of the national NEXRAD radar network for all weather radar applications.
		The phased array radar project has begun a new stage in NSSL's leadership in the research and development of future generations of weather radar.
	www.norman.noaa.gov /publicaffairs/backgrounders/backgrounder_par.html (645 words)

	Acoustic Applications of Phased Array Technology
		Phased arrays synthesize larger apertures from an array of elements.
		Phased arrays get around the beam width limit by using several small apertures to achieve the same result as one large aperture.
		Before we explore the workings of a phased array, it should be noted that the equations and science here makes no distinction between receiving and transmitting devices.
	casa.colorado.edu /~danforth/science/sonar/sonar1.html (2782 words)

	Tutorial 5.5 Phased Array Design and Applications
		Phased array antennas an enabling technology for modern radar systems, provide the diversity needed to raise the performance of radar systems far beyond the capabilities of rotating antenna radars of the past.
		Today’s modern phased arrays incorporate active components for high average transmit power, superior low noise performance, and independent element level phase and amplitude control.
		Applications of phased array technology will be discussed with examples from current and future systems.
	www.radar04.org /program/index.cgi?paper=69 (541 words)

	Phased-Array Acoustic Imaging
		Aeroacoustic test applications have used phased arrays of microphones to measure the acoustic source distributions of jets and wind-tunnel models of aircraft.
		The use of aeroacoustic phased arrays for real aircraft in flight was pioneered by Ulf Michel at the German Research Laboratory (DLR).
		They progressed to planar arrays on the ground that are similar in layout to arrays developed by Boeing for wind tunnel testing.
	www.acoustic-imaging.com /array.html (1136 words)

	AN/FPS-115 PAVE PAWS Radar
		Phased array antenna aiming, or beam steering, is done rapidly by electronically controlling the timing, or phase, of the incoming and outgoing signals.
		A phased array antenna, as any other directional antenna, will receive signals from space only in the direction in which the beam is aimed.
		PAVE is an Air Force program name, that, contrary to some reports, does not have an expansion, while PAWS stands for Phased Array Warning System.
	www.fas.org /spp/military/program/track/pavepaws.htm (1816 words)

	Computer Controlled Phased Array
		The problem in any phased array is getting the phase and magnitude of the currents in each of the elements to be properly set to produce the desired pattern.
		Here are some rules of thumb for phased array design which are handy to make sure that you don't expect too much or too little.
		Their directivity will be around 45-50, which implies that there are 50 or so orientations that are useful (25 actually, considering it you have to cover a hemisphere, but double it because it lets you space the positions closer than the -3 dB points).
	home.earthlink.net /~jimlux/radio/antenna/phased/phased1.htm (1279 words)

	K-Band Phased Array for LEO Satellite Communications
		Under a cooperative agreement, an MMIC-based, K-band phased-array antenna is being developed with 50/50 cost sharing by the NASA Lewis Research Center and Raytheon Systems Company.
		Soon after the array is completed, Lewis plans to integrate it into a flight experiment to test its operation in the space environment.
		The transmitting array, which will operate at 19 gigahertz (GHz), is a state-of-the-art design that features dual, independent, electronically steerable beam operation (±42°), a stand-alone thermal management, and a high-density tile architecture.
	www.grc.nasa.gov /WWW/RT1998/5000/5640anzic.html (360 words)

	Georgia Tech: Phased Array Antennas and Adaptive Techniques
		The principles of phased array antennas are covered first, followed by the details of the underlying hardware.
		These laboratories are either interactive computer simulation labs that allow students to become familiar with phased array design techniques and trade-offs, presentations of array hardware, or demonstrations on how to use the near-field range to make antenna pattern measurements, detect faults, or phase align an array.
		The student should leave with a thorough understanding of the nature of phased arrays, their construction and design, and the many adaptive processing approaches they enable.
	www.pe.gatech.edu /conted/servlet/edu.gatech.conted.course.ViewCourseDetails;jsessionid=14C359CE1817FD4C4CB705E4D3D85BDC?COURSE_ID=521 (415 words)

	Phased Array Antennas - WiFi-Forum
		Phased Array Antenna is a highly interesting and facinating concept.
		How this was achieved is based on the idea that the array of antennas can tell which direction a signal comes from by calculating the reception delay between each antenna on the array, like how we workout where a sound is coming from with our ears.
		Then this is followed by using signal reinforcement and destruction to extend the lobes (or beams) to reach the user by varying the variables of each antenna on the array.
	www.wifi-forum.com /wf/showthread.php?t=352 (582 words)

	Phased Array-Based Systems and Applications
		Phased Array-Based Systems and Applications was written for researchers and engineers with a professional interest in phased array-based systems.
		Timely, authoritative, and comprehensive, it discusses the most current uses of phased arrays (operating at cm and mm wavelengths) in radar, radio astronomy, remote sensing, electronic warfare, spectrum surveillance, and communications.
		This exploration of systems that share the same principles and perform similar functions helps phased array users in all these fields learn more about the systems and applications in which they specialize.
	www.scitechpub.com /Fourikis.htm (175 words)

	Ka-Band Multibeam Aperture Phased Array Being Developed
		One effort to reduce the cost of phased arrays is the development of a Ka-band multibeam aperture (MBA) phased array by Boeing Corporation under a contract jointly by the NASA Glenn Research Center and the Office of Naval Research.
		Fabrication of a 16-element prototype array is scheduled for the middle of fiscal year 2004, with a full-scale 256-element array in the middle of fiscal year 2005.
		The arrays can be constructed to conform to a mounting surface, and multibeam capability is integral to the design.
	www.grc.nasa.gov /WWW/RT/2003/5000/5650reinhart1.html (499 words)

	Phased Array Discussions - June 2000
		My current phased antennas are two 30 feet long 15 feet high noise reducing inverted L antennas, separated about 150 feet, on a north-south line, with the horizontal parts of the inverted L antennas perpendicular to the line connecting the bases of the vertical parts, and oriented in the same direction.
		Phased broadband loops may give wider nulls, as Dallas seems to have indicated by reference to the article by O. Villard.
		Arrays with two (or more) broadband loops might even be better than ones comprised of broadband active whips.
	home.comcast.net /~markwa1ion/exaol1/phased_arrays.htm (3640 words)

	Wiley::Phased Array Antennas : Floquet Analysis, Synthesis, BFNs and Active Array Systems
		Incorporating the most recent developments in phased array technology, Phased Array Antennas is an essential resource for students of phased array theory, as well as research professionals and engineers engaged in the design and construction of phased array antennas.
		In addition, numerous design examples and guidelines will be found highly useful by those engaged in the practical application of this new approach to phased array structures.
		Engineers, researchers, and advanced graduate students involved in phased array antenna technology will find this systematic presentation an invaluable reference.
	eu.wiley.com /WileyCDA/WileyTitle/productCd-0471727571.html (349 words)

	Pms Seminar: Phased Array Radar Design
		This is a 3-day course covering both the principles and technology of the phased array antenna itself and the overall system significance, design and the operation the phased array permits.
		Here he was responsible for much of the formative work in the AN/SPY-1 phased array radar for the AEGIS.
		He was given increasing responsibilities until he became civilian director of the Naval Sea Systems command's radar group which covered all US Navy shipboard surveillance radars.
	www.pms.se /seminars/phasedarr.htm (179 words)

	Raptor Reliability Software Example - Phased Array Radar
		Large-scale phased array radar systems, generally located in geographically remote areas, are used by the military as early warning devices.
		To simulate a portion of this phased array radar face reliability model using Raptor 7.0, contact Kenneth E. Murphy (kenneth.murphy@arinc.com) and request the PhaseArray.rbd file.
		In this example, Raptor was used to develop a reliability model for a phased array radar system.
	www.arinc.com /products/raptor/examples/phase_array_radar.html (152 words)

	Microwave Journal: A THINNED MULTIBEAM PHASED ARRAY.@ HighBeam Research
		A single-aperture four-beam phased-array antenna that integrates four thinned, nonuniform (or density tapered) phased arrays into a 52.4 wavelength diameter aperture is described.
		The resultant four-beam array element count is 68 percent of a filled array with a 1 [degrees] half-power beamwidth (HPBW).
		Each beam array's element count is less than 18 percent of a filled array.
	www.highbeam.com /library/doc0.asp?DOCID=1G1:59184852&refid=holomed_1 (202 words)

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In the News (Thu 31 Dec 09)