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Sunday, September 1, 2013

Active electronically scanned array

From Wikipedia, the free encyclopedia



APAR AESA onboard Hamburg (F220), a Sachsen-class frigate of the German Navy
An active electronically scanned array (AESA), also known as active phased array radar is a type of phased array radar whose transmitter and receiver functions are composed of numerous small solid-state transmit/receive modules (TRMs). AESA radars aim their "beam" by emitting separate radio waves from each module that interfere constructively at certain angles in front of the antenna. They improve on the older passive electronically scanned radars by spreading their signal emissions out across a band of frequencies, which makes it very difficult to detect over background noise. AESAs allow ships and aircraft to broadcast powerful radar signals while still remaining stealthy.

Basic concept

Radar systems generally work by connecting an antenna to a powerful radio transmitter to emit a short pulse of signal. The transmitter is then disconnected and the antenna is connected to a sensitive receiver which amplifies any echos from target objects. By measuring the time it takes for the signal to return, the radar receiver can determine the distance to the object. The receiver then sends the resulting output to a display of some sort. The transmitter elements were typically klystron tubes or magnetrons, which are suitable for amplifying or generating a narrow range of frequencies to high power levels. To scan a portion of the sky, the radar antenna must be physically moved to point in different directions.
Starting in the 1960s new solid-state devices capable of delaying the transmitter signal in a controlled way were introduced. That led to the first practical large-scale passive electronically scanned array (PESA), or simply phased array radar. PESAs took a signal from a single source, split it into hundreds of paths, selectively delayed some of them, and sent them to individual antennas. The radio signals from the separate antennas overlapped in space, and the interference patterns between the individual signals was controlled to reinforce the signal in certain directions, and mute it in all others. The delays could be easily controlled electronically, allowing the beam to be steered very quickly without moving the antenna. A PESA can scan a volume of space much quicker than a traditional mechanical system. Additionally, thanks to progress in electronics, PESAs added the ability to produce several active beams, allowing them to continue scanning the sky while at the same time focusing smaller beams on certain targets for tracking or guiding semi-active radar homing missiles. PESAs quickly became widespread on ships and large fixed emplacements in the 1960s, followed by airborne sensors as the electronics shrank.
AESAs are the result of further developments in solid-state electronics. In earlier systems the transmitted signal was originally created in a klystron or traveling wave tube or similar device, which are relatively large. Receiver electronics were also large due to the high frequencies that they worked with. The introduction of gallium arsenide microelectronics through the 1980s served to greatly reduce the size of the receiver elements, until effective ones could be built at sizes similar to those of handheld radios, only a few cubic centimeters in volume. The introduction of JFETs and MESFETs did the same to the transmitter side of the systems as well. Now an entire radar, the transmitter, receiver and antenna, could be shrunk into a single "transmitter-receiver module" (TRM) about the size of a carton of milk.
The primary advantage of a AESA over a PESA is capability of the different modules to operate on different frequencies. Unlike the PESA, where the signal is generated at single frequencies by a small number of transmitters, in the AESA each module generates and radiates its own independent signal. This allows the AESA to produce numerous "sub-beams" and actively "paint" a much larger number of targets. Additionally, the solid-state transmitters are able to transmit effectively at a much wider range of frequencies, giving AESAs the ability to change their operating frequency with every pulse sent out. AESAs can also produce beams that consist of many different frequencies at once, using post-processing of the combined signal from a number of TRMs to re-create a display as if there was a single powerful beam being sent.

Advantages

AESAs add many capabilities of their own to those of the PESAs. Among these are: the ability to form multiple beams, to use each TRM for different roles concurrently, like radar detection, and, more importantly, their multiple simultaneous beams and scanning frequencies create difficulties for traditional, correlation-type radar detectors.

Low probability of intercept

See also: low probability of intercept radar
Radar systems work by sending out a signal and then listening for its echo off distant objects. Each of these paths, to and from the target, is subject to the inverse square law of propagation. That means that a radar's received energy drops with the fourth power of the distance, which is why radar systems require high powers, often in the megawatt range, to be effective at long range.[1]
The radar signal being sent out is a simple radio signal, and can be received with a simple radio receiver. It is common to use such a receiver in the targets, normally aircraft, to detect radar broadcasts. Unlike the radar unit, which must send the pulse out and then receive its reflection, the target's receiver does not need the reflection and thus the signal drops off only as the square of distance. This means that the receiver is always at an advantage over the radar in terms of range - it will always be able to detect the signal long before the radar can see the target's echo. Since the position of the radar is extremely useful information in an attack on that platform, this means that radars generally must be turned off for lengthy periods if they are subject to attack; this is common on ships, for instance.
Turning that received signal into a useful display is the purpose of the "radar warning receiver" (RWR). Unlike the radar, which knows which direction it is sending its signal, the receiver simply gets a pulse of energy and has to interpret it. Since the radio spectrum is filled with noise, the receiver's signal is integrated over a short period of time, making periodic sources like a radar add up and stand out over the random background. Typically RWRs store the detected pulses for a short period of time, and compare their broadcast frequency and pulse repetition frequency against a database of known radars. The rough direction can be calculated using a rotating antenna, or similar passive array using phase or amplitude comparison, and combined with symbology indicating the likely purpose of the radar - airborne early warning, surface to air missile, etc. Integration over time is also used to the advantage of an LPI radar. Instead of short, powerful pulses, a radar may extend their duration and lower their power. This makes no difference to the total power reflected by the target but makes the detection of the pulse by an RWR system less likely.[2]
This technique is much less useful against AESA radars. Since the AESA (or PESA) can change its frequency with every pulse (except when using doppler filtering), and generally does so using a pseudo-random sequence, integrating over time does not help pull the signal out of the background noise. Nor does the AESA have any sort of fixed pulse repetition frequency, which can also be varied and thus hide any periodic brightening across the entire spectrum. Older generation RWRs are essentially useless against AESA radars. Modern RWRs must be made highly sensitive (small angles and bandwidths for individual antennas, low transmission loss and noise)[2] and add successive pulses through time-frequency processing to achieve useful detection rates.[3]

High jamming resistance

Jamming is likewise much more difficult against an AESA. Traditionally, jammers have operated by determining the operating frequency of the radar and then broadcasting a signal on it to confuse the receiver as to which is the "real" pulse and which is the jammer's. This technique works as long as the radar system cannot easily change its operating frequency. When the transmitters were based on klystron tubes this was generally true, and radars, especially airborne ones, had only a few frequencies to choose among. A jammer could listen to those possible frequencies and select the one to be used to jam.
Most radars using modern electronics are capable of changing their operating frequency with every pulse. An AESA has the additional capability of spreading its frequencies across a wide band even in a single pulse, which equates to lowering the emission power, making jammers much less effective. Although it is possible to send out broadband white noise against all the possible frequencies, this means the amount of energy being sent at any one frequency is much lower, reducing its effectiveness. In fact, AESAs can then be switched to a receive-only mode, and use these powerful jamming signals instead to track its source, something that required a separate receiver in older platforms. However, using a single antenna only gives a direction. Obtaining a range and a target vector requires at least two physically separate passive devices for triangulation to provide instantaneous determinations. Target motion analysis can estimate these quantities by incorporating many directional measurements over time, along with knowledge of the position of the receiver and constraints on the possible motion of the target.
AESA radars can be much more difficult to detect, and so much more useful in receiving signals from the targets, that they can broadcast continually and still have a very low chance of being detected. This allows such radar systems to generate far more data than traditional radar systems, which can only receive data periodically, greatly improving overall system effectiveness.

Other advantages

Since each element in a AESA is a powerful radio receiver, active arrays have many roles besides traditional radar. One use is to dedicate several of the elements to reception of common radar signals, eliminating the need for a separate radar warning receiver. The same basic concept can be used to provide traditional radio support, and with some elements also broadcasting, form a very high bandwidth data link. The F-35 uses this mechanism to send sensor data between aircraft in order to provide a synthetic picture of higher resolution and range than any one radar could generate. In 2007, tests by Northrop Grumman, Lockheed Martin, and L-3 Communications enabled the AESA system of a Raptor to act like a WiFi access point, able to transmit data at 548 megabits per second and receive at gigabit speed; this is far faster than the Link 16 system used by US and allied aircraft, which transfers data at just over 1 Mbit/s.[4]
AESAs are also much more reliable than either a PESA or older designs. Since each module operates independently of the others, single failures have little effect on the operation of the system as a whole. Additionally, the modules individually operate at low powers, perhaps 40 to 60 watts, so the need for a large high-voltage power supply is eliminated.
Replacing a mechanically scanned array with a fixed AESA mount (such as on the F/A-18E/F Super Hornet) can help reduce an aircraft's overall radar cross-section (RCS), but some designs (such as the Eurofighter Typhoon) forgo this advantage in order to combine mechanical scanning with electronic scanning and provide a wider angle of total coverage.[5]

Limitations

The highest Field of View (FOV) for a flat phased array antenna is currently 120°, however this can be combined with mechanical steering as noted above.[6]

List of existing systems

US based manufacturers of the AESA radars used in the F22 and Super Hornet include Northrop Grumman[7] and Raytheon.[8] These companies also design, develop and manufacture the transmit/receive modules which comprise the 'building blocks' of an AESA radar. The requisite electronics technology was developed in-house via Department of Defense research programs such as MIMIC Program.[9][10]

Airborne systems

Ground and Maritime based systems

  • APAR (active phased array radar): Thales' multifunction radar is the primary sensor of the Royal Netherlands Navy's De Zeven Provinciën class frigates, the German Navy's Sachsen class frigates, and the Royal Danish Navy's Ivar Huitfeldt class frigates. APAR is the first active electronically scanned array multifunction radar employed on an operational warship.[13]
  • Selex EMPAR (European Multifunction Phased Array Radar)
  • Elta
    • EL/M-2080 Green Pine ground-based early warning AESA radar
    • EL/M-2248 MF-STAR multifunction naval radar
    • EL/M-2258 ALPHA multifunction naval radar
    • EL/M-2084 multimission radar (artillery weapon location, air defence and fire control)
    • EL/M-2133 WindGuard - Trophy active protection system radar
  • Northrop Grumman
    • AN/TPS-80 Ground/air task-oriented radar (G/ATOR)
    • HAMMR Highly mobile multi-mission radar
  • Raytheon
    • U.S. National Missile defense X-Band radar (XBR)
    • AN/SPY-3 multifunction radar for U.S. DD(X), CG(X) and CVN-21 next-generation surface vessels
  • ThalesRaytheonSystems
  • MEADS's fire control radar
  • Type H/LJG-346(8) on Chinese aircraft carrier ex-Varyag
  • Type 348 Radar on Type 052C destroyer
  • AESA radar on Type 052D destroyer
  • H/LJG-346 SAPARS (Predecessor to the Type 348 Radar on Type 052C destroyer)
  • Type 305A Radar (Acquisition radar for the HQ-9 missile system)[14]
  • YLC-2 Radar[15]
  • THAAD system fire control radar
  • Type-03 Medium Range Surface-to-Air MissileSystem (Chu-SAM,SAM-4) multifunction radar
  • BAE Systems Insyte SAMPSON multifunction radar for UK Type 45 destroyers
  • FCS-3 Mitsubishi Electric Corporation (Melco)
  • OPS-24 Mitsubishi Electric Corporation (The world's first Naval Active Electronically Scanned Array radar)
  • J/FPS-3 Japanese main ground-based air defense radar produced by Melco
  • J/FPS-4 Cheaper than J/FPS-3, produced by Toshiba
  • J/FPS-5 Japanese ground-based next-generation missile defense radar
  • J/TPS-102 Self-propelled ground-based radar, cylindrical array antenna, NEC
  • JMPQ-P13 Counter-battery radar, Toshiba
  • JTPS-P14 Transportable air defence radar, Melco
  • JTPS-P16 Firefinder radar, Melco
  • CEAFAR CEA Technologies A 4th generation multifunction digital active phased array radar, installed on HMAS Perth and to be installed on all ANZAC class frigates.
  • NNIIRT 1L119 Nebo SVU mobile AESA 3-dimensional surveillance radar
  • VNIIRT Gamma DE mobile 3-dimensional solid-state AESA surveillance radar

See also

AN/APG-81

From Wikipedia, the free encyclopedia
AN/APG-81
AN-APG-81 Antenna, 2005 - National Electronics Museum - DSC00393.JPG
Country of origin United States
Type Solid-state active electronically scanned array (AESA)  

The AN/APG-81 is an active electronically scanned array (AESA) radar system designed by Northrop Grumman Electronic Systems for the Lockheed Martin F-35 Lightning II.
The Joint Strike Fighter AN/APG-81 AESA radar is a result of the US government's competition for the world's largest AESA acquisition contract. Westinghouse Electronic Systems (acquired by Northrop Grumman in 1996) and Hughes Aircraft (acquired by Raytheon in 1997) received contracts for the development of the Multifunction Integrated RF System/Multifunction Array (MIRFS/MFA) in February 1996.[1] Lockheed Martin and Northrop Grumman were selected as the winners of the Joint Strike Fighter competition; The System Development and Demonstration (SDD) contract was announced on 26 October 2001.
The AN/APG-81 is a successor radar to the F-22's AN/APG-77. Over three thousand AN/APG-81 AESA radars are expected to be ordered for the F-35, with production to run beyond 2035, and including large quantities of international orders. As of October 2013, over one hundred APG-81s have already been produced and delivered. The first three blocks of radar software have been developed, flight tested, and delivered ahead of schedule by the Northrop Grumman Corporation.
Capabilities of the AN/APG-81 include the AN/APG-77's air-to-air modes, plus advanced air-to-ground modes, including high resolution mapping, multiple ground moving target indication and track, combat identification, electronic warfare, and ultra high bandwidth communications. The current F-22 production radar is the APG-77v1, which draws heavily on APG-81 hardware and software for its advanced air-to-ground capabilities.[2]
In August 2005, the APG-81 radar was flown for the first time aboard Northrop Grumman's BAC 1–11 test aircraft. Since then, the radar system has accumulated over 300 flight hours. The first radar flight on Lockheed Martin's CATBird avionics test-bed occurred in November 2008.[3]
In June 2009, the F-35s APG-81 active electronically scanned array radar was integrated in the Northern Edge 2009 large-scale military exercise when it was mounted on the front of a Northrop Grumman test aircraft. The test events "validated years of laboratory testing versus a wide array of threat systems, showcasing the extremely robust electronic warfare capabilities of the world's most advanced fighter fire-control radar."[4]
Announced on 22 June 2010: The radar met and exceeded its performance objectives successfully tracking long-range targets as part of the first mission systems test flights of the F-35 Lightning II BF-4 aircraft.[3]
The AN/APG-81 team won the 2010 David Packard Excellence in Acquisition Award for performance against jammers.[5]

AMDR

From Wikipedia, the free encyclopedia

This article is about Air and Missile Defense Radar. For Acceptable Macronutrient Distribution Ranges, see Dietary Reference Intake.
 
An Arleigh Burke class destroyer
 
The AMDR (Air and Missile Defense Radar) is an active electronically scanned array[1] air and missile defense radar under development for the United States Navy.[2] It will provide integrated air and missile defense, and even periscope detection, for the Flight III Arleigh Burke class destroyers.[3]

Development

On October 10, 2013, "Raytheon Company (RTN) [was] awarded a $385,742,176 cost-plus-incentive-fee contract for the engineering and modeling development phase design, development, integration, test and delivery of Air and Missile Defense S-band Radar (AMDR-S) and Radar Suite Controller (RSC)." [4] In September 2010, the Navy awarded technology development contracts to Northrop Grumman, Lockheed Martin, and Raytheon to develop the S-band radar and radar suite controller (RSC). X-band radar development reportedly will come under separate contracts. The Navy hopes to place AMDR on Flight III Arleigh Burke class destroyer, possibly beginning in 2016. Those ships currently mount the Aegis Combat System system, produced by Lockheed Martin.[5]
In 2013, the Navy cut almost $10 billion from the cost of the program by adopting a smaller less capable system that will be challenged by "future threats".[6] As of 2013 the program is expected to deliver 22 radars at a total cost of $6,598m; they will cost $300m/unit in serial production.[7] Testing is planned for 2021 and Initial operating capability is planned for March 2023.[7] The Navy then was forced to halt the contract in response to a challenge by Lockheed.[8] Lockheed officially withdrew their protest and the Navy lifted the stop work on January 10th, 2014.[9]

Technology

The AMDR system consists of two primary radars and a radar suite controller (RSC) to coordinate the sensors. An S-band radar is to provide volume search, tracking, ballistic missile defense discrimination and missile communications while the X-band radar is to provide horizon search, precision tracking, missile communication and terminal illumination of targets.[5] The S-band and X-band sensors will also share functionality including radar navigation, periscope detection, as well as missile guidance and communication. AMDR is intended as a scalable system; the Burke deckhouse can only accommodate a 14-foot version but the USN claim they need a radar of 20 foot or more to meet future ballistic missile threats.[7] This would require a new ship design; Ingalls have proposed the San Antonio-class amphibious transport dock as the basis for a ballistic missile defense cruiser with 20-foot AMDR. To cut costs the first twelve AMDR sets will have an X-band component based on the existing SPQ-9B rotating radar, to be replaced by a new X-band radar in set 13 that will be more capable against future threats.[7] The transmit-receive modules will use new gallium nitride semiconductor technology.[7] This will allow for higher power density than the previous gallium arsenide radar modules.[10]
Although it was not an initial requirement, the AMDR may be capable of performing electronic attacks using its AESA antenna. Airborne AESA radar systems, like the APG-77 used on the F-22 Raptor, and the APG-81 and APG-79 used on the F-35 Lightning II, F/A-18 Super Hornet, and EA-18G Growler have demonstrated their capability to conduct electronic attack. The contenders for the Navy's Next Generation Jammer all used Gallium Nitride-based (GaN) transmit-receiver modules for their EW systems, which enables the possibility that the high-power GaN-based AESA radar used on Flight III ships can perform the mission. Precise beam steering could attack air and surface threats with tightly directed beams of high-powered radio waves to electronically blind aircraft, ships, and missiles.[11]

SAMPSON

From Wikipedia, the free encyclopedia

For other uses, see Sampson (disambiguation).
SAMPSON
SAMPSON-rotation-composite-3.jpg
2012 composite photographed at less than one second interval showing SAMPSON antenna rotation.
 
Country of origin United Kingdom
Number built 6 (ordered)
Type Solid-state AESA radar
Frequency 2-4 GHz (S band)
Range 400 km[1]
Power 25kW

The SAMPSON is a multi-function dual-face active electronically scanned array radar produced by BAE Systems Maritime. It is the fire control radar component of the Sea Viper naval air defence system, previously designated PAAMS(S) to distinguish it from the PAAMS system on the Franco-Italian Horizon Class.
The SAMPSON multi function radar can detect all types of targets out to a distance of 400 km, and is capable of tracking hundreds of targets at any one time. Sea Viper uses this information to assess and command target priorities, and calculate the optimum launch time for its Aster missiles.

History

SAMPSON is derived from the Multi-function Electronically Scanned Adaptive Radar (MESAR) programme. MESAR 1 development commenced in 1982 as a partnership between Plessey, Roke Manor Research and the Defence Evaluation and Research Agency.[2][3] Plessey was acquired by Siemens in 1989 to become Siemens-Plessey, itself acquired by British Aerospace in 1998. British Aerospace became BAE Systems in November 1999. MESAR 1 trials occurred between 1989 and 1994.[2] MESAR 2 development began in August 1995, of which SAMPSON is a derivative.[4]
The Royal Navy intended to deploy the SAMPSON MFR on its version of the Horizon CNGF - a collaboration with France and Italy to produce anti-air warfare frigates. Following delays and complications the UK withdrew and started its own Type 45 programme. The Type 45 destroyers use the SAMPSON radar with the PAAMS missile system, which was also developed for the Horizon frigates (French and Italian ships are to be fitted with the EMPAR MFR). The SAMPSON Radar is made in Cowes, Isle of Wight.

Operation

HMS Daring SAMPSON multi-function AESA radar
 
Conventional radars, consisting of a rotating transmitter and sensor, have limited power, are vulnerable to enemy jamming and perform only one function - with separate units therefore required for surveillance, tracking and targeting.
As an active array, SAMPSON uses software to shape and direct its beam allowing several functions to be carried out at once and, through adaptive waveform control, is virtually immune to enemy jamming. Active arrays have both longer range and higher accuracy than conventional radars. The beam-directing software uses sophisticated algorithms to schedule looks so that the potentially hundreds of active tracks are maintained with maximum accuracy.[5]
The SAMPSON uses two planar arrays to provide coverage over only part of the sky; complete coverage is provided by rotating the arrays, essentially similar to the way conventional radar systems operate. This is in contrast to the US AN/SPY-1 system (as used on the Ticonderoga class cruiser and Arleigh Burke class destroyer) or the Dutch/German/Canadian APAR system (as used on the Royal Dutch Navy's De Zeven Provinciën class frigates, the German Navy's Sachsen class frigates, and the Royal Danish Navy's Ivar Huitfeldt class frigates), which use multiple arrays fixed in place to provide continuous coverage of the entire sky. Whilst this may seem to be a disadvantage, the SAMPSON radar rotates at 30 revolutions per minute, meaning no part of the sky lacks coverage for more than one second on average - the precise time varies as the beams can also be swept back and forth electronically. In addition, the use of a smaller number of arrays allows the system to be much lighter, allowing placement of the arrays at the top of a prominent mast rather than on the side of the superstructure as in the US ships. Placing any radar emitter at higher altitude extends the horizon distance, improving performance against low level targets (see Sea skimming); SAMPSON is at approximately double the height above the waterline than the arrays of its US equivalents. Although precise details of the SAMPSON's performance in this regard are unlikely to enter the public domain, such factors may mitigate the disadvantages of fewer arrays.
BAE Systems have also claimed that Sampson eliminates the need for several separate systems. They suggest that on the Type 45 destroyer, the Alenia Marconi Systems/Signaal [now Thales Nederland] S 1850M long-range 3D radar that is designed to work in partnership with Sampson "really is superfluous and is not needed to perform the mission of the ship". BAE Systems believes that the reason the large volume search radar has been incorporated into PAAMS is "more of a historic nature, associated with [the] work sharing issues" that were a huge problem during the trilateral Project Horizon.

Some tasks are difficult to combine, for example (long range) volume search takes a lot of radar resources, leaving little room for other tasks such as targeting. Combining volume search with other tasks also results either in slow search rates or in low overall quality per task. Driving parameters in radar performance is time-on-target or observation time per beam. This is perhaps a the [sic] key reason why the Royal Navy selected the S1850M Long Range Radar to complement Sampson on the Type 45 destroyers. It is also a reason why NATO in its NATO Anti-Air Warfare System study (NAAWS) defined the preferred AAW system as consisting of a complementary Volume Search Radar and MFR. This - as NATO points out - gives the added advantage that the two systems can use two different radar frequencies; one being a good choice for long range search, the other a good choice for an MFR (which is especially nice as physics makes both tasks difficult to combine).[3]
The performance of both the SAMPSON radar and the PAAMS' Aster missiles will give the Royal Navy an anti-air warfare capability to replace its long serving Type 42 destroyers. The first Type 45, HMS Daring was launched on February 1 2006. The ship was fitted with SAMPSON and S1850M radars in 2007. She underwent trials before being commissioned 20 April 2012.

Modes

  • Long and medium-range search
  • Surface picture search
  • High-speed horizon search
  • High-angle search and track
  • Multiple target tracking and multiple channel fire control.

EMPAR

From Wikipedia, the free encyclopedia

EMPAR (European Multifunction Phased Array Radar) is a rotating G band multifunction passive electronically scanned array radar built by Selex ES (previously SELEX Sistemi Integrati). It is designed to be the principal radar system aboard naval vessels of medium and large sizes. The radar offers full volumetric search coverage, low altitude and surface search, the tracking of multiple targets, and the capability to uplink information for missile guidance.

Details

EMPAR's principal function is 3D volumetric air search, providing a bearing, range and altitude for air traffic out to ranges of 300 miles. It is capable of tracking aircraft or smaller targets such as missiles. The system employs a single narrow beam for transmission, plus multiple beams for reception. These can be steered electronically, allowing the EMPAR to scan very rapidly across a wide angle of bearing and/or elevation. It thus provides the simultaneous monitoring of an entire hemisphere.[1] The flat face of the radar is rotated at 60 rpm, allowing it to sweep across the whole sky very rapidly. The system therefore provides an almost continuous 360 degree view,[2] in contrast to earlier rotating radar systems which often took ten seconds or more to sweep the sky. This capability is important to air defence systems given the great speed of modern anti ship missiles such as the P-270 Moskit or Brahmos.
EMPAR continuously analyses the data it receives and will automatically adapt the frequency and waveform it is using as necessary. As with all phased array radars it is difficult to jam or interfere with and can work in the presence of intense clutter. EMPAR is compatible with the PAAMS system, providing guidance to Aster 15 or 30 missiles for medium or long range air defence.[3]

Employment

Empar is in use on the Horizon class Frigate for France and Italy, the Italian Cavour class aircraft carrier and the Italian FREMM Frigate Carlo Bergamini.

Active Phased Array Radar

From Wikipedia, the free encyclopedia

This article is about a specific radar model named APAR. For application of Active Phased Array Radar as generic term describing a type of radar, see active electronically scanned array.
 
APAR mounted on top of the German Navy Sachsen class frigate Hamburg's superstructure.
 
Rear side of APAR on board the German Navy Sachsen class frigate Hessen.
 
Active Phased Array Radar (APAR) is a shipborne multifunction radar (MFR) developed and manufactured by Thales Nederland. It is the first active electronically scanned array MFR employed on an operational warship.[1]

Characteristics

APAR has four fixed (i.e., non-rotating) sensor arrays (faces), fixed on a pyramidal structure. Each face consists of 3424 transmit/receive (TR) modules operating at X band frequencies.[2]
The radar provides the following capabilities:
  • air target tracking of over 200 targets out to 150 km[2]
  • surface target tracking of over 150 targets out to 32 km[2]
  • horizon search out to 75 km[2]
  • "limited" volume search out to 150 km[2] (in order to back up the volume search capabilities of the SMART-L)
  • cued search (a mode in which the search is cued using data originating from another sensor)
  • surface gunfire support[2]
  • missile guidance using the Interrupted Continuous Wave Illumination (ICWI) technique, thus allowing guidance of 32 semi-active radar homing missiles in flight simultaneously, including 16 in the terminal guidance phase[3]
  • "innovative" Electronic Counter-Countermeasures (ECCM)[2]
Note: all ranges listed above are instrumented ranges.

Mountings

APAR aboard the Royal Netherlands Navy De Zeven Provinciën class frigate HNLMS Tromp.
 
APAR aboard the German Navy Sachsen class frigate Hessen at Kiel Week 2007.
 
APAR is installed on four Royal Netherlands Navy (RNLN) LCF De Zeven Provinciën class frigates, three German Navy F124 Sachsen class frigates, and three Royal Danish Navy Ivar Huitfeldt class frigates. The Netherlands and Germany (along with Canada) were the original sponsors for the development of APAR, whereas Denmark selected APAR for their frigates as part of a larger decision to select a Thales Nederland anti-air warfare system (designed around the APAR and SMART-L radars, the Raytheon ESSM and SM-2 missile systems, and the Lockheed Martin Mk-41 vertical launch system) over the competing Sea Viper (previously designated PAAMS (S)) anti-air warfare system (designed around the BAE Systems SAMPSON radar, the MBDA Aster 15/30 missile systems, and the MBDA SYLVER vertical launch system).

Live Missile Firings

APAR's missile guidance capability supports the Evolved Sea Sparrow Missile (ESSM) and the SM-2 Block IIIA missile. In November 2003, approximately 200 nautical miles (370 km) from the Azores, the missile guidance capabilities were tested with live firings for the first time.[3] The firings were performed by the RNLN's HNLMS De Zeven Provinciën and involved the firing of a single ESSM and a single SM-2 Block IIIA. These firings were the first ever live firings involving a full-size ship-borne Active Electronically Scanned Array guiding missiles using the ICWI technique in an operational environment.[4] As related by Jane's Navy International:
During the tracking and missile-firing tests, target profiles were provided by Greek-built EADS/3Sigma Iris PVK medium-range subsonic target drones. [...] According to the RNLN, ... "APAR immediately acquired the missile and maintained track until destruction". [...] These ground-breaking tests represented the world's first live verification of the ICWI technique.[3]
In August 2004, a German Navy Sachsen class frigate completed a series of live missile firings at the Point Mugu missile launch range off the coast of California that included a total of 11 ESSM and 10 SM-2 Block IIIA missiles.[3] The tests included firings against target drones such as the Northrop Grumman BQM-74E Chukkar III and Teledyne Ryan BQM-34S Firebee I, as well as against missile targets such as the Beech AQM-37C and air-launched Kormoran 1 anti-ship missiles.[3]
Further live firings were performed by the RNLN's HNLMS De Zeven Provinciën in March 2005, again in the Atlantic Ocean approximately 180 nautical miles (330 km) west of the Azores.[3] The tests involved three live-firing events including firing a single SM-2 Block IIIA at an Iris target drone at long range, a single ESSM at an Iris target drone, and a two-salvo launch (with one salvo comprising two SM-2 Block IIIAs and the other comprising two ESSMs) against two incoming Iris target drones.[3] The long-range SM-2 engagement apparently resulted in an intercept at a range of greater than 100 km from the ship, with a missile-target miss distance of 2,4m/8 feet (the warhead's proximity fuse having been disabled for the purposes of the test).[3]

Operational Concept

APAR is typically paired with Thales Nederland's SMART-L passive electronically scanned array radar (which operates at L band frequencies). SMART-L is a long-range Volume Search Radar (VSR) that is able to provide volume search and tracking out to 480 km. The whole system is called Anti-Air Warfare Systems (AAWS), and is based on the NATO Anti-Air Warfare (NAAWS) concept of the late 1980s. The principle behind this concept is that an X band MFR coupled with an L band VSR provides the optimal combination of complementary capabilities: the VSR is optimized for long range detection and tracking of targets, while the MFR is optimized for medium range high accuracy tracking of targets, as well as horizon search and missile guidance functions.
As discussed below, some have questioned the optimality of separate MFR/VSR installations on-board ship. However, the wisdom of NATO's concept is evident to this author:
BAE Systems have also claimed that Sampson eliminates the need for several separate systems. They suggest that on the Type 45 destroyer, the Alenia Marconi Systems/Signaal [now Thales Nederland] S1850M long-range 3D radar that is designed to work in partnership with Sampson "really is superfluous and is not needed to perform the mission of the ship". BAE Systems believes that the reason the large volume search radar has been incorporated into PAAMS is "more of a historic nature, associated with [the] work sharing issues" that were a huge problem during the trilateral Project Horizon.

Some tasks are difficult to combine, for example (long range) volume search takes a lot of radar resources, leaving little room for other tasks such as targeting. Combining volume search with other tasks also results either in slow search rates or in low overall quality per task. Driving parameters in radar performance is time-on-target or observation time per beam. This is perhaps a the [sic] key reason why the Royal Navy selected the S1850M Long Range Radar to complement Sampson on the Type 45 destroyers. It is also a reason why NATO in its NATO Anti-Air Warfare System study (NAAWS) defined the preferred AAW system as consisting of a complementary Volume Search Radar and MFR. This - as NATO points out - gives the added advantage that the two systems can use two different radar frequencies; one being a good choice for long range search, the other a good choice for an MFR (which is especially nice as physics makes both tasks difficult to combine).[5]

Counter-Piracy Operations

Ships of the RNLN's De Zeven Provinciën class have been involved in counter-piracy operations off the Horn of Africa. The untraditional target set (i.e., small slow-moving or even static surface targets) can apparently be challenging for doppler radars designed to take on "high end" threats. However, according to Jane's International Defence Review:
[The RNLN has] reported great success using tailored surface-search software for the APAR sets fitted to the De Zeven Provinciën-class frigates deployed on anti-piracy roles. By sacrificing some of APAR's high-end anti-air warfare capabilities, which were deemed unnecessary for the anti-piracy role, its performance and resolution were improved in the surface-search role.[6]
The exploits of the RNLN's De Zeven Provinciën class frigate HNLMS Tromp in regards to counter-piracy operations — including the April 2010 rescue of the container ship MV Taipan — are described here. The counter-piracy exploits of the HNLMS Evertsen are outlined here.

Next Generation Jammer

From Wikipedia, the free encyclopedia

The Next Generation Jammer is a program to develop an airborne electronic warfare system, as a replacement for the AN/ALQ-99 found on the EA-18G military aircraft. It will reach Initial Operating Capability in 2021.

Platforms

The AN/ALQ-99 is currently mounted on EA-6B Prowler and EA-18G Growler aircraft of the U.S. Navy and, in the case of the EA-6B Prowler only, U.S. Marine Corps.
In the primary role of suppression of air defenses, these aircraft are to provide modified escort jamming from outside the range of known surface to air missiles.[1]

History

The poor reliability of the ALQ-99 and frequent failures of the Built In Test (BIT) have caused crew to fly missions with undetected faults; the ALQ-99 also interferes with the aircraft's AESA radar, reduces the top speed of the aircraft and imposes a high workload on the two man crew.[2]
The United States Marine Corps is considering replacing their Northrop Grumman EA-6B Prowler electronic attack aircraft with F-35s that have stealthy jammer pods attached.[3] On 30 September 2008, the United States Navy outlined the basic requirements of the NGJ and stated that the design must be modular and open.[4] The Navy has selected four companies to submit designs for the Next Generation Jammer.[5] The NGJ will also have cyber attack capabilities where the AESA radar is used to insert tailored data streams into remote systems.[6][7] The ITT-Boeing design for the NGJ includes six AESA arrays for all around coverage.[8][9] The team has been awarded a $42 million contract to develop their design based on ITT's experience with broadband electronically steerable antenna arrays.[10] At the same time contracts were also awarded to Raytheon, Northrop Grumman and BAE Systems.[11]
After having existing jamming platforms thinly stretched over three wars during Operation Odyssey Dawn, the Navy accelerated the NGJ program and anticipated a vendor selection in 2013 instead of 2015 as previously planned.[12]
All contractors bidding for the program have included Active Electronically Scanned Array technology in their plans.[13]
The Office of Naval Research has started a Next-Generation Airborne Electronic Attack (NGAEA) project to develop technologies for the NGJ.[14]
The system was expected to be fielded (on the Growler) by 2020,[15] but budget cuts pushed IOC to 2021.[16] Tom Burbage of Lockheed Martin has said that the NGJ would be carried by his company's F-35 in 2022 or 2023.[17] Marine Corps Commandant Gen. James Amos has said that unlike previous generations of aircraft, the base EW systems in the standard F-35 will allow it to just attach the pods and perform the mission, without having to make a special electronic warfare version of the F-35.[18][citation needed]
On July 8th, 2013 it was announced by Navair that the $279 million Technical Development (TD) phase of the contract had been awarded to Raytheon Space and Airborne Systems.[19][20][21] On 26 July 2013, the Navy issued Raytheon a stop-work order, following a formal protest of the contract by BAE Systems.[22] On 18 December 2013, the Government Accountability Office upheld the protest, claiming they found that the Navy used improper procedures to select Raytheon. The Navy examined the issue and continued with Raytheon.[23]
In 2013 Boeing invested their own funds in a series of upgrades that they believe will be needed for the Growler to field the NGJ.[24]
After a successful System Readiness Review in June 2014, Raytheon expects to move forward with flight testing in September 2014 and an IOC of late 2020. The test was flown in November 2014.[25] The pod operates independently of the aircraft's systems, automatically responding to identified threats. One unique aspect of the NGJ is that its AESA array combines EW, coms, radar, and signals intelligence; AESA is known to perform EW and radar, but also handling SIGINT and serving as a communications array are new capabilities. Other than dedicated EW aircraft, the pods can be installed on other platforms like the UCLASS with little modification.[26]

AN/APG-79

From Wikipedia, the free encyclopedia
  (Redirected from APG-79)

The AN/APG-79 Active electronically scanned array (AESA) radar is a new development for the United States Navy's F/A-18E/F Super Hornet and Boeing EA-18G Growler aircraft, providing a high level of aircrew situational awareness. The beam of the AESA radar provides nearly instantaneous track updates and multi-target tracking capability. The APG-79 AESA uses transmit/receive (TR) modules populated with Gallium arsenide Monolithic microwave integrated circuits.[1] In the F/A-18E/F, the radar is installed in a slide-out nose rack to facilitate maintenance.
The APG-79 features an entirely solid-state antenna construction, which improves reliability and lowers the cost compared to a traditional system. The radome of the APG-79 for the F/A-18E/F slides forward instead of hinging to the right, which saves space in aircraft carrier hangars.[citation needed][clarification needed]
The APG-79 is compatible with current F/A-18 weapon loads and enables aircrew to fire the AIM-120 AMRAAM, simultaneously guiding several missiles to several targets widely spaced in azimuth, elevation or range.
The APG-79 radar completed formal operational evaluation (OPEVAL) testing in December 2006. As of January 2007 the radar was installed in 28 aircraft; some were experiencing software problems but that issue was expected to be resolved by the end of fiscal year 2007.[2] As of July 2008, Raytheon had delivered 100 APG-79 sets to the Navy; on 3 June 2008, the Navy received the first APG-79-equipped Boeing EA-18G Growler. The Navy expects to order approximately 400 production radars.[3]
In January 2013, the Director of Test & Evaluation (DOT&E) disclosed a long history of problems for the APG-79 radar in initial operational testing.[4]
• DOT&E reported on APG-79 radar IOT&E [initial operational test and evaluation] in FY07, assessing it as not operationally effective or suitable due to significant deficiencies in tactical performance, reliability, and BIT functionality.
• The Navy conducted APG-79 radar FOT&E [follow-on test and evaluation] in FY09 in conjunction with SCS H4E SQT. The Navy’s Commander, Operational Test and Evaluation Force subsequently reported that significant deficiencies remained for both APG-79 AESA performance and suitability; DOT&E concurred with this assessment.
• The APG-79 AESA radar demonstrated marginal improvements since the previous FOT&E period and provides improved performance relative to the legacy APG-73 radar. However, operational testing does not demonstrate a statistically significant difference in mission accomplishment between F/A-18E/F aircraft equipped with AESA and those equipped with the legacy radar.
• Full development of AESA electronic warfare capability remains deferred to later software builds.
No date was predicted for the F/A-18 E/F Hornet's APG-79 radar reaching an operationally suitable status.

Monolithic microwave integrated circuit

From Wikipedia, the free encyclopedia

Photograph of a GaAs MMIC (a 2–18 GHz upconverter)
 
MMIC MSA-0686.
 
A Monolithic Microwave Integrated Circuit, or MMIC (sometimes pronounced "mimic"), is a type of integrated circuit (IC) device that operates at microwave frequencies (300 MHz to 300 GHz). These devices typically perform functions such as microwave mixing, power amplification, low-noise amplification, and high-frequency switching. Inputs and outputs on MMIC devices are frequently matched to a characteristic impedance of 50 ohms. This makes them easier to use, as cascading of MMICs does not then require an external matching network. Additionally, most microwave test equipment is designed to operate in a 50-ohm environment.
MMICs are dimensionally small (from around 1 mm² to 10 mm²) and can be mass-produced, which has allowed the proliferation of high-frequency devices such as cellular phones. MMICs were originally fabricated using gallium arsenide (GaAs), a III-V compound semiconductor. It has two fundamental advantages over silicon (Si), the traditional material for IC realisation: device (transistor) speed and a semi-insulating substrate. Both factors help with the design of high-frequency circuit functions. However, the speed of Si-based technologies has gradually increased as transistor feature sizes have reduced, and MMICs can now also be fabricated in Si technology. The primary advantage of Si technology is its lower fabrication cost compared with GaAs. Silicon wafer diameters are larger (typically 8" or 12" compared with 4" or 6" for GaAs) and the wafer costs are lower, contributing to a less expensive IC.
Originally, MMICs used MEtal-Semiconductor Field-Effect Transistors (MESFETs) as the active device. More recently High Electron Mobility Transistors (HEMTs), Pseudomorphic HEMTs and Heterojunction Bipolar Transistors have become common.
Other III-V technologies, such as indium phosphide (InP), have been shown to offer superior performance to GaAs in terms of gain, higher cutoff frequency, and low noise. However they also tend to be more expensive due to smaller wafer sizes and increased material fragility.
Silicon germanium (SiGe) is a Si-based compound semiconductor technology offering higher-speed transistors than conventional Si devices but with similar cost advantages.
Gallium nitride (GaN) is also an option for MMICs. Because GaN transistors can operate at much higher temperatures and work at much higher voltages than GaAs transistors, they make ideal power amplifiers at microwave frequencies.

Military Embedded Systems

Multifunction, high-performance AESA radar leads a transformation of the battlefield sensor network

Dr. Douglas J. Carlson MACOM

3 

Active electronically scanned array (AESA) radar systems built with gallium nitride (GaN)-based radio frequency (RF) power components are helping to elevate the capabilities of the modern networked battlefield.

Multifunction () is making significant inroads into the modern . AESA radar is featured in technologies such as the () capability – developed by Raytheon and soon to be installed on the U.S. Navy’s EA-18 Growler air fleet – bringing conventional and advanced cyber defense capabilities together via an AESA radar-based platform.
Advanced AESA radar is also coming to U.S. Air Force F-16s by way of Northrop Grumman’s () technology; Raytheon’s Advanced Combat Radar (RACR) has also emerged as a similar AESA technology platform, offering the ability to simultaneously detect, identify, and track multiple air and surface targets. Every member of has announced AESA upgrade programs based on these and other platforms.
Next-gen radar for increased situational awareness
This evolution of the modern battlefield is being driven by the need for improved connectivity and situational awareness to ensure mission success in the face of unpredictable and dynamic adversaries. The modern fighting force needs to be equipped with advanced and communication infrastructure designed to operate as a unified, highly versatile mesh network that distributes critical data across ground, sea, and air domains at previously unimaginable speeds and bandwidths.
To enable continuous, high-performance data distribution throughout the modern battlefield, the underlying sensor mesh must operate as a homogenous network, adapt quickly to changing operating conditions, and be highly resilient to ensure that the loss of individual sensor nodes throughout the network doesn’t compromise the integrity or effectiveness of the network itself. Next-generation radar systems are therefore critical to providing situational awareness beyond the single platform of operation to the entire networked battlefield. To meet these complex needs, advanced radar systems are transitioning away from conventional radar architectures that rely on mechanical steering – which are prone to limitations in agility and reliability due to size, weight, and functionality – and turning toward AESA radar systems that offer key performance advantages and multifunction capability.
With AESA technology, the mechanical gimbal is eliminated. Scanning is handled electronically via stationary arrays comprised of hundreds to thousands of transmit and receive elements. This array architecture enables simultaneous functions ranging from radar surveillance and fire control to jamming and advanced data link . Based on incoming information from nodes across the network, an AESA radar system can be called upon to aid a battle scenario by providing surveillance, jamming an enemy signal, or targeting and eliminating a threat.
Multifunction AESA versatility also enables dramatic improvements in target tracking. Conventional radar systems are optimized for either ultra-high-speed tracking of immediate threats, or long-range tracking of distant targets, but typically not both. Multirole AESA radar can combine these capabilities to allow for high-precision, multi-target tracking spanning both short- and long-range threats. It is easy to imagine how this advanced tracking capability could be applied in a fighter jet cockpit, enabling pilots to detect and visualize a considerably higher number of approaching enemy aircraft and missiles than they can today.
Power for performance
Accelerating the forward progress toward next-generation multifunction AESA radar that strengthens and expands the battlefield sensor network hinges on the ability to develop and manufacture smaller, lighter, wider-bandwidth, and more energy-efficient power components that promote multifunction integration. What is needed in all of these cases is a new approach to power component design and packaging that provides greater overall power performance in a smaller form factor with the greatest possible ease of assembly.
AESA radar system designers can achieve high-power operation with improved efficiency while accelerating time to market by using the newly emerging -based RF power components that can be assembled using highly automated commercial techniques. Improved efficiency and lighter-weight system design also enable AESA systems to be placed onto smaller operational platforms – such as (UAVs) – that would otherwise be unable to provide critical sensor data in the battlefield.
These new GaN-driven capabilities are yielding a new generation of agile AESA radar systems optimized to meet the increasingly demanding performance and multifunction flexibility requirements of the modern battlefield. Among the many advantages that GaN offers for multifunction AESA radar systems are high-power operation, improved power efficiency, reduced system size and weight, and wide-bandwidth operation (see Figure 1).
GaN delivers minimally eight times the raw power density of incumbent GaAs technology, while boosting efficiency from mid-40 percent to as high as 70 percent depending on the frequency of operation. At the radar system level, the high-output power enabled by GaN-based RF components ultimately enables increased range surveillance with improved resolution in smaller platforms. This capability ensures that AESA radar systems are better equipped to distinguish real from false targets more accurately and alert the operator of threats more quickly. The ability to emit higher power also enables greater flexibility with regard to shaping the signal pulses without compromising on overall system performance.
21
Figure 1: The on silicon carbide (GaN on SiC) pulsed power transistor for military and civilian radar pulsed applications offers designers a typical 17 W of peak output power with 63 percent efficiency.
(Click graphic to zoom by 1.9x)
The higher breakdown voltage performance of GaN allows for scaling to higher operational voltages, which leads to improved efficiency in the device and therefore the radar system’s power supply. Higher efficiency reduces system-cooling requirements, which are a significant contributor to weight and power consumption, and enables longer mission operation before refueling in mobile platforms such as UAVs and ground units.
GaN in plastic-packaged RF power components has set a new standard for harnessing high power in small enclosures implementing surface-mount assembly, thereby eliminating many of the size and weight limitations of conventional ceramic-packaged GaN-based offerings. This aspect is particularly important given the accelerating proliferation of -mounted AESA radar systems. For UAVs, any reduction in the size and weight of the underlying components has a direct, positive impact on the aircraft’s flight range and operational versatility.
Moreover, the high voltage thresholds of GaN-based RF power components enable increased wideband impedance matching. This capability enables an AESA radar system to perform multifunctional roles across a broader frequency spectrum with increased operational flexibility.
The need for speed
Time to market is a critical consideration for modern military systems, with multifunction AESA radar systems no exception. Design and manufacturing cycles must be accelerated wherever possible to keep pace with rapidly evolving threats. In the electronic warfare domain, the proliferation of (IEDs) in urban battle zones has necessitated ever-faster prototyping, testing, and manufacturing of sophisticated -jamming devices that aim to minimize roadside casualties and equipment damage. The five- to 10-year design cycles that currently characterize large radar development programs – targeted at large platforms such as aircraft carriers, other warships, and fighter aircraft – will undoubtedly become increasingly as new threats emerge with increasing frequency and are countered with more agile and flexible platforms such as UAVs.
The clear battlefield advantages enabled by multifunction AESA radar make this technology a prime candidate for intensified attention to design and manufacturing efficiency. GaN-based RF power components that support standard () assembly lets developers accelerate time to market by leveraging commercial best practices for high-volume manufacturing, ensuring a host of additional benefits including improved assembly yield, lower component count, and reduced-touch labor. By enabling the use of SMT throughout the manufacturing process, radar system manufacturers can avoid the need for cumbersome cutouts, coining, and flange assembly (see Figure 2).
22
Figure 2: MACOM’s family of gallium nitride on silicon carbide (GaN on SiC) RF power hybrid amplifiers – optimized for military radar applications – supports standard surface-mount assembly, enabling designers to realize improved assembly yield, lower component count, and reduced-touch labor.
(Click graphic to zoom by 1.9x)
Tight integration at the embedded component level reduces the space required for each RF element and reduces the number of overall components needed to be procured, which naturally helps accelerate lead time. Aggregate reduction in part count also minimizes the risk of performance variation from component to component.
Innovation advantage
Continued innovation in GaN-based RF power components promises to accelerate the trend toward advanced, multifunction AESA radar systems by introducing significant benefits including improved power, efficiency, and operational agility; reduced system size and weight; and shorter time to market. As this technology makes its way into the integrated mesh network of sensors that underpins the modern battlefield, it will enhance the potency and agility of our fighting forces for decades to come.
Dr. Douglas J. Carlson received his Sc.B. in Electronic Material from Brown University in 1983 and his Sc.D. in Electronic Materials from the Massachusetts Institute of Technology in 1989. Dr. Carlson subsequently served on the research staffs of MIT and Bell Laboratory. In 1990, Dr. Carlson joined MACOM in its Advanced Semiconductor Division; his current position is Vice President of Strategy. Readers may contact him at douglas.carlson@macom.com.

Gallium Nitride Based Active Electronically Scanned Array (AESA) Technology for High Altitude Periscope Detection

Navy SBIR 2013.2 - Topic N132-095
NAVAIR - Ms. Donna Moore - navair.sbir@navy.mil
Opens: May 24, 2013 - Closes: June 26, 2013


N132-095 TITLE: Gallium Nitride Based Active Electronically Scanned Array (AESA) Technology for High Altitude Periscope Detection

TECHNOLOGY AREAS: Air Platform, Electronics

ACQUISITION PROGRAM: PMA 264

RESTRICTION ON PERFORMANCE BY FOREIGN CITIZENS (i.e., those holding non-U.S. Passports): This topic is "ITAR Restricted". The information and materials provided pursuant to or resulting from this topic are restricted under the International Traffic in Arms Regulations (ITAR), 22 CFR Parts 120 - 130, which control the export of defense-related material and services, including the export of sensitive technical data. Foreign Citizens may perform work under an award resulting from this topic only if they hold the "Permanent Resident Card", or are designated as "Protected Individuals" as defined by 8 U.S.C. 1324b(a)(3). If a proposal for this topic contains participation by a foreign citizen who is not in one of the above two categories, the proposal will be rejected.

OBJECTIVE: Develop an innovative single integrated Gallium Nitride (GaN) transmit and receive (T/R) Monolithic Microwave Integrated Circuit (MMIC) system, and the corresponding array technology that enables a low cost, high performance, thin, efficient, low size, weight and power (SWaP), and high altitude submarine periscope detection capability.

DESCRIPTION: Commercial processes routinely produce GaN High Power Amplifiers (HPA), High Power Switches (HPS), and Low Noise Amplifiers (LNAs) as separate packaged parts. A main objective is to design a compact T/R MMIC system that performs all these functions in one small package to enable a very thin flat 2D Active Electronically Scanned Array (AESA) at C-band. GaN is capable of producing a fully integrated T/R MMIC, but has to be done in concert with the design restrictions of flat AESA approaches. In comparison to Gallium Arsenide, Gallium Nitride HPAs can operate at higher voltage and junction temperatures. The higher voltage enables higher efficiencies which along with higher junction temperatures and higher thermal conductivity enable easier thermal management design. Current GaN AESA thermal designs enable over 2 watts per square inch average transmit power relatively independent of frequency.

The GaN T/R MMIC system should be designed to optimally enable the design of a complete AESA radar. The system should include the AESA radiating surface and back end manifolds, analog Radio Frequency (RF) receivers, exciter, frequency source, beam steering, radar control, and Input/Output digitization. The system level interface to the AESA should be completely digital via Gigabit Ethernet or equivalent. Flat panel AESA system(s) and GaN devices should use industry standard modeling and design tools. Designs should consider the needs of the system and receiver/exciter for radar applications.

An innovative and integrated GaN MMIC and array technology enables a thin, efficient, low SWaP, low cost, high performance radar antenna that can then be easily installed on a large number of space constrained platforms.

PHASE I: Develop and prove feasibility of a GaN T/R MMIC based 2D C-band AESA for high altitude periscope detection.

PHASE II: Further develop and demonstrate a prototype of the system developed in Phase I.

PHASE III: Finalize testing and transition the technology to the appropriate platforms and the Fleet.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: The technology is directly applicable to both commercial communication/data link systems and radar systems.

REFERENCES:
1. Reese, E., Allen, D., Lee, C., & Nguyen, T. (2010). Wideband Power Amplifier MMICs Utilizing GaN on SiC. Richardson, Texas: TriQuint Semiconductor. Retrieved from: http://www.triquint.com/shared/pubs/symposiums/Eli%20Reese%20on%20GaN%20Wideband%20Amplifiers.pdf

2. Palmour, J.W., Hallin, C., Burk, A., Radulescu, F., Namishia, D., Hagleitner, H., Duc, J., Pribble, B., Sheppard, S.T., Barner, J.B., & Milligan, J. (2010). 100 mm GaN-on-SiC RF MMIC Technology. Microwave Symposium Digest (MTT), 2010 IEEE MTT-S International, 1226-1229. doi: 10.1109/MWSYM.2010.5515973

KEYWORDS: Radar, Phased Array, Gallium Nitride, Active Electronically Scanned Array, T/R Modules, Periscope Detection

** TOPIC AUTHOR (TPOC) **DoD Notice: Between April 24 through May 24, 2013, you may talk directly with the Topic Authors (TPOC) to ask technical questions about the topics. Their contact information is listed above. For reasons of competitive fairness, direct communication between proposers and topic authors is not allowed starting May 24, 2013, when DoD begins accepting proposals for this solicitation.

However, proposers may still submit written questions about solicitation topics through the DoD's SBIR/STTR Interactive Topic Information System (SITIS), in which the questioner and respondent remain anonymous and all questions and answers are posted electronically for general viewing until the solicitation closes. All proposers are advised to monitor SITIS (13.2 Q&A) during the solicitation period for questions and answers, and other significant information, relevant to the SBIR 13.1 topic under which they are proposing.

If you have general questions about DoD SBIR program, please contact the DoD SBIR Help Desk at (866) 724-7457 o
r email weblink. 

Radar jamming and deception

From Wikipedia, the free encyclopedia
 
 Radar jamming and deception (Electronic countermeasure) is the intentional emission of radio frequency signals to interfere with the operation of a radar by saturating its receiver with noise or false information. There are two types of radar jamming: Mechanical and Electronic jamming.

Contents

Mechanical jamming

Mechanical jamming is caused by devices which reflect or re-reflect radar energy back to the radar to produce false target returns on the operator's scope. Mechanical jamming devices include chaff, corner reflectors, and decoys.
  • Chaff is made of different length metallic strips, which reflect different frequencies, so as to create a large area of false returns in which a real contact would be difficult to detect. Modern chaff is usually aluminum coated glass fibers of various lengths. Their extremely low weight and small size allows them to form a dense, long lasting cloud of interference.
  • Corner reflectors have the same effect as chaff but are physically very different. Corner reflectors are multiple-sided objects that re-radiate radar energy mostly back toward its source. An aircraft cannot carry as many corner reflectors as it can chaff.
  • Decoys are maneuverable flying objects that are intended to deceive a radar operator into believing that they are actually aircraft. They are especially dangerous because they can clutter up a radar with false targets making it easier for an attacker to get within weapons range and neutralize the radar. Corner reflectors can be fitted on decoys to make them appear larger than they are, thus furthering the illusion that a decoy is an actual aircraft. Some decoys have the capability to perform electronic jamming or drop chaff. Decoys also have a deliberately sacrificial purpose i.e. defenders may fire guided missiles at the decoys, thereby depleting limited stocks of expensive weaponry which might otherwise have been used against genuine targets.

Electronic jamming

German Luftwaffe Tornado ECR.
 
Electronic jamming is a form of electronic warfare where jammers radiate interfering signals toward an enemy's radar, blocking the receiver with highly concentrated energy signals. The two main technique styles are noise techniques and repeater techniques. The three types of noise jamming are spot, sweep, and barrage.
  • Spot jamming occurs when a jammer focuses all of its power on a single frequency. While this would severely degrade the ability to track on the jammed frequency, a frequency agile radar would hardly be affected because the jammer can only jam one frequency. While multiple jammers could possibly jam a range of frequencies, this would consume a great deal of resources to have any effect on a frequency-agile radar, and would probably still be ineffective.
  • Sweep jamming is when a jammer's full power is shifted from one frequency to another. While this has the advantage of being able to jam multiple frequencies in quick succession, it does not affect them all at the same time, and thus limits the effectiveness of this type of jamming. Although, depending on the error checking in the device(s) this can render a wide range of devices effectively useless.
  • Barrage jamming is the jamming of multiple frequencies at once by a single jammer. The advantage is that multiple frequencies can be jammed simultaneously; however, the jamming effect can be limited because this requires the jammer to spread its full power between these frequencies, as the number of frequencies covered increases the less effectively each is jammed.
  • Base jamming is a new type of Barrage Jamming where one radar is jammed effectively at its source at all frequencies. However, all other radars continue working normally.
  • Pulse jamming produces noise pulses with period depending on radar mast rotation speed thus creating blocked sectors from directions other than the jammer making it harder to discover the jammer location.
  • Cover pulse jamming creates a short noise pulse when radar signal is received thus concealing any aircraft flying behind the EW craft with a block of noise.
  • Digital radio frequency memory, or DRFM jamming, or Repeater jamming is a repeater technique that manipulates received radar energy and retransmits it to change the return the radar sees. This technique can change the range the radar detects by changing the delay in transmission of pulses, the velocity the radar detects by changing the doppler shift of the transmitted signal, or the angle to the plane by using AM techniques to transmit into the sidelobes of the radar. Electronics, radio equipment, and antenna can cause DRFM jamming causing false targets, the signal must be timed after the received radar signal. By analysing received signal strength from side and backlobes and thus getting radar antennae radiation pattern false targets can be created to directions other than one where the jammer is coming from. If each radar pulse is uniquely coded it is not possible to create targets in directions other than the direction of the jammer
  • Deceptive jamming uses techniques like "range gate pull-off" to break a radar lock.[1][2]

Inadvertent jamming

In some cases, jamming of either type may be caused by friendly sources. Inadvertent mechanical jamming is fairly common because it is indiscriminate and will affect any nearby radars, hostile or not. Electronic jamming can also be inadvertently caused by friendly sources, usually powerful EW platforms operating within range of the affected radar. Unintentional electronic jamming is most easily prevented by good planning and common sense, though sometimes it is unavoidable.

Countermeasures

  • Constantly alternating the frequency that the radar operates on (frequency hopping) over a spread-spectrum will limit the effectiveness of most jamming, making it easier to read through it. Modern jammers can track a predictable frequency change, so the more random the frequency change, the more likely it is to counter the jammer.
  • Cloaking the outgoing signal with random noise makes it more difficult for a jammer to figure out the frequency that a radar is operating on.
  • Limiting unsecure radio communication concerning the jamming and its effectiveness is also important. The jammer could be listening, and if they know that a certain technique is effective, they could direct more jamming assets to employ this method.
  • The most important method to counter radar jammers is operator training. Any system can be fooled with a jamming signal but a properly trained operator pays attention to the raw video signal and can detect abnormal patterns on the radar screen.
  • The best indicator of jamming effectiveness to the jammer is countermeasures taken by the operator. The jammer does not know if their jamming is effective before operator starts changing radar transmission settings.
  • Using EW countermeasures will give away radar capabilities thus on peacetime operations most military radars are used on fixed frequencies, at minimal power levels and with blocked Tx sectors toward possible listeners (country borders)
  • Mobile fire control radars are usually kept passive when military operations are not ongoing to keep radar locations secret
  • Active electronically scanned array (AESA) radars are innately harder to jam and can operate in Low Probability of Intercept (LPI) modes to reduce the chance that the radar is detected.
  • A quantum radar system would automatically detect attempts at deceptive jamming, which might otherwise go unnoticed.[3]

Stealth

Stealth technologies like Radar-absorbent materials can be used to reduce the return of a target.

Interference

While not usually caused by the enemy, interference can greatly impede the ability of an operator to track. Interference occurs when two radars in relatively close proximity (how close they need to be depends on the power of the radars) are operating on the same frequency. This will cause "running rabbits", a visual phenomenon that can severely clutter up a scope with useless data. Interference is not that common between ground radars, however, because they are not usually placed close enough together. It is more likely that some sort of airborne radar system is inadvertently causing the interference—especially when two or more countries are involved.
The interference between airborne radars referred to above can sometimes (usually) be eliminated by frequency-shifting the magnetron.
The other interference often experienced is between the aircraft's own electronic transmitters, i.e. transponders, being picked up by own radar. This interference is eliminated by suppressing the radar's reception for the duration of the transponder's transmission. Instead of "bright-light" rabbits across the display, one would observe very small black dots. Because the external radar causing the transponder to respond is generally not synchronised with your own radar (i.e. different PRFs [pulse repetition frequency]), these black dots appear randomly across the display and the operator sees through and around them. The returning image may be much larger than the "dot" or "hole", as it has become known, anyway. Keeping the transponder's pulse widths very narrow and mode of operation (single pulse rather than multi-pulse) becomes a crucial factor.
The external radar could, in theory, come from an aircraft flying alongside your own, or from space. Another factor often overlooked is to reduce the sensitivity of one's own transponder to external radars; i.e., ensure that the transponder's threshold is high. In this way it will only respond to nearby radars—which, after all, should be friendly.
One should also reduce the power output of the transponder in like manner.

Jamming police radar

Jamming radar for the purpose of defeating police radar guns is more simple than military-grade radar jamming.[4]

Jamming in nature

The jamming of bat sonar by certain tiger moth species has recently been confirmed.[5]
 

http://www.thedailybeast.com/

 
 
To suggest that the F-35 is VHF-stealthy is like arguing that the sky is not blue—literally, because both involve the same phenomenon. The late-Victorian physicist Lord Rayleigh gave his name to the way that electromagnetic radiation is scattered by objects that are smaller than its wavelength. This applies to the particles in the air that scatter sunlight, and aircraft stabilizers and wingtips that are about the same meter-class size as VHF waves.
The counter-stealth attributes of VHF have been public knowledge for decades. They were known at the dawn of stealth, in 1983, when the MIT’s Lincoln Laboratory ordered a 150-foot-wide radar to emulate Russia’s P-14 Oborona VHF early-warning system. Lockheed Martin’s Fort Worth division—makers of the F-35—should know about that radar: they built it.
Making a plane VHF-stealthy starts with removing the target’s tails, as on the B-2 bombers. But we did not know how to do that on a supersonic, agile airplane (like the F-35 is supposed to be) when the JSF specifications were written.
Neither did the technology to add broadband-active jamming to a stealth aircraft exist in 1995. Not only did stealth advocates expect jamming to fade away, but there was an obvious and (at the time) insoluble problem: To use jamming you have to be certain that the radar has detected you. Otherwise, jamming is going to reveal your presence and identify you as a stealth aircraft, since the adversary can see a signal but not a reflection.
We can be sure that onboard jamming has not been added to the F-35 since. Had the JSF requirements been tightened by one iota since the program started, its advocates would be blaming that for the delays and overruns.
“To suggest that the F-35 is stealthy is like arguing that the sky is not blue – literally, because both involve the same phenomenon.”
What the JSF does have is a jamming function—also known as “electronic attack,” or EA, in militaryese—in the radar. It also has an expendable radar decoy—BAE Systems’ ALE-70. Both are last-ditch measures to disrupt a missile engagement, not to prevent tracking.
JSF’s planners, in the mid-1990s, were close to correct when they calculated that low-band stealth and limited EA, combined with passive electronic surveillance for situational awareness, would be adequate at service entry. But they expected that the F-35 would reach squadrons in 2010, and China’s military modernization was barely imaginable.
The threats of the late 2010s will be qualitatively different. Old VHF radars could be dealt with by breaking the kill chain between detection and tracking: they did not provide good enough cueing to put analog, mechanically scanned tracking radars on to the target. Active electronically scanned array (AESA), high-power VHF radars and decimeter- and centimeter-wave trackers are more tenacious foes.
Last August, at an air show near Moscow, I talked to designers of a new, highly mobile counterstealth radar system, now being delivered to the Russian armed forces. Its centerpiece was a 100-foot-wide all-digital VHF AESA, but it also incorporated powerful higher-frequency radars that can track small targets once the VHF radar has detected them. More recently, however, it has emerged that the U.S. Navy is worried because new Chinese warships carry the Type 517M VHF search radar, which its maker says is an AESA.
None of this is to say that stealth is dead, but it is not reasonable to expect that the cat-and-mouse game of detection and evasion in air combat has stopped, or that it ever will. EA and stealth still do not coexist very comfortably on the same platform, but offboard EA and stealth are synergistic: the smaller the target, the less jamming power is needed to mask it.
But the threat’s demonstrated agility drives home the lesson that there is no one winning move in the radar game. Excessive reliance on a single-point design is not a good idea, and using fictitious secrecy to quash the debate is an even worse one.
This column also appears in the April 28 issue of Aviation Week & Space Technolog
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