The advent of production Active Electronically Steered Array (AESA) radar antennas represents one of the most important, if not the most important development in radar technology since the 1940s. With unprecedented reliability, superior performance and typically of the order of a one thousandfold improvement in beamsteering speeds, this technology will transform many aspects of air combat and strike operations.

The idea of an electronically steered antenna is not new. Early warning radars used for the detection of ballistic missile attacks have exploited this technology widely since the 1960s. The US Navy's SPY-1 Aegis radar, developed during the 1970s to defend carrier battle groups against saturation attacks by Soviet cruise missiles, is perhaps the best known electronically steered antenna design in operational use.

The B-1B Bone has flown since the 1980s with an AN/APQ-164 radar, fitted with an electronically steered array. The B-1A Batwing also exploits this technology in its AN/APQ-181 multimode attack radar. Both of these radars can be used for terrain following flight, as well as surface attack modes. The Soviet MiG-31 Foxhound also carries this technology in its SBI-16 Zaslon air intercept radar.

The important and recent development in electronically steered antennas is the solid state X-band (centimetric wavelength) AESA, built using Gallium Arsenide chips. This technology is now being retrofitted to in-service fighters and will be a standard production component in the F-22A and F-35 series fighters, and most likely a downstream production/upgrade item for late model F-16C, F/A-18E/F, Typhoon and Rafale fighters.

Active Electronically Steered Arrays - A Primer

To best understand the importance of the AESA it is useful to explore the limitations of conventional mechanically steered antennas, and the first generation of passive Electronically Steered Arrays (ESA).

The basic purpose of any microwave radar antenna on a fighter (or bomber) is to focus transmitted microwave power into a narrow beam, or receive reflected microwave power from targets (or terrain), again within a narrowly focussed beamwidth. Targets are found by steering the antenna repetitively through a programmed pattern, to search a volume of sky or a surface footprint. The antenna transmits the energy, which travels out to the target, reflects and is then received by the antenna. For an antenna to be useful it must therefore not only be capable of launching and receiving microwave power, but must be steerable precisely and preferably very quickly.

The one bit of good news in antenna physics is the reciprocity theorem which says that the radiation pattern of an antenna when transmitting power is of the same shape as its reception pattern.

In an ideal world the antenna produces an absolutely sharp beam - the radiation pattern is for instance conical, and all energy transmitted is within that cone, and all energy detected by the antenna is also within that cone. In the real world this of course does not happen, the radiation pattern leaks outside the main lobe of the beam, creating what are termed sidelobes. A good measure of antenna quality is how small the sidelobes are eg ten times (10 deciBels or dB), one hundred times (20 dB), or one thousand times (30 dB) below the mainlobe in magnitude.

The first generation of microwave fighter radar antennas were mechnically steered concave reflectors, colloquially termed dish antennas. This is the basic technology the RAAF still operates in the F-111's AN/APQ-169 and -171 radars. These antennas have several drawbacks - they are expensive to fabricate to high accuracy, tend to have fairly large sidelobes, and also have a frequently large radar signature when illuminated by a hostile radar - as all concave reflecting cavities do.

By the 1970s the state of the art shifted to mechanically steered planar array or slotted array antennas, an example being the AN/APG-65/73 radar in the RAAF's F/A-18A. Planar arrays achieve their focussing effect not by reflection as concave antennas do, but rather by manipulating the individual time delays into a very large number of very simple slot antennas, arranged in a planar array panel. By using a cleverly designed and oft complex network of microwave waveguides on the rear surface of the array, a designer could produce the desired fixed beam shape and do so with much smaller sidelobes compared to a concave reflecting antenna. As the antenna is a flat plate, it tends to act like a flat panel reflector to impinging transmissions from hostile radars and thus has a lower radar signature than a concave antenna.

While the US focussed on planar arrays, the Europeans and Soviets deployed a number of Cassegrainian reflector antennas on fighter radars, as these performed better than concave reflectors but were cheaper to design and fabricate than planar arrays - the design and manufacture of the complex feed networks on the rear face of any array antenna is still considered to be somewhat a black art.

Planar arrays provided important gains in beam quality but due to the need to mechanically point them they remained slow to steer and also suffered the same reliability problems as concave antennas. The complex mechanical gimbal arrangement and servomotors used to drive such antennas suffer from wearout, and the cyclic mechanical loads on the antenna proper can also induce material fatigue failures over time.

Airborne radar designers covetously eyed the electronically steered antenna technology used on ground based radars and by the 1980s this technology found its way into airborne radars, some examples noted earlier. An electronically steered antenna of this ilk is designed with an individually electronically controlled device behind each antenna element, which can manipulate the time delay or phase of the microwave signal passing through it. With a computer controlling each element in unison, the beam direction and its shape could be digitally controlled, within a matter of milliseconds or tens of milliseconds.

The first generation of such antennas used the signal phase as the controlling parameter, typically using ferrite core devices for this purpose. Therefore such antennas were known as phased arrays. A typical design could resemble a conventional planar array, but with a layer of digitally controlled ferrite core phase modules inserted between the antenna array elements and the microwave feed network on the back of the antenna. As the antenna contained only what engineers term passive components, these antennas are also known as passive phased arrays or passive electronically steered arrays. The Russian SBI-16 Zaslon, Phazotron Zhuk Ph and NIIP N-011M are good examples, as are the AN/APQ-164 and -181 mentioned earlier.

This generation of Electronically Steered Arrays permitted unprecedented beam seering agility compared to mechanically steered antennas, and very large reductions in antenna radar signature if well designed. Beamsteering agility in turn permitted the important capability of interleaving radar modes. An ESA can timeshare multiple and diverse modes, a good example being shared concurrent operation performing both terrain following and surface mapping for weapon delivery.

However, the antenna did nothing to enhance either the reliability or the efficiency of the radar. The high power Travelling Wave Tube in the transmitter remained, causing its traditional share of reliability woes, while the complex interconnections required to connect the digital control signals to the wirewound ferrite cores was an additional burden. Since the ferrite cores introduced signal losses in both the receiving and transmitting directions, these antennas were less sensitive than their mechanically steered predecessors, and required more powerful microwave tubes to drive them.

The US DoD recognised the need for a better antenna technology more than two decades ago. A new technology, using the phased array concept but with a miniature transmitter and receiver in each antenna element, was seen to be the answer to the limitations of existing technologies. Known as active phased arrays or AESAs, these antennas became the holy grail in the radar community - for reasons yet to become fully apparent.

The enabling technology for AESAs is the Gallium Arsenide Microwave Monolithic Integrated Circuit (GaAs MMIC) or microwave circuit on a single chip. GaAs MMICs would permit the low cost mass production of AESAs, with high reliability and repeatability.

Gallium Arsenide is however a finicky material to make chips from and it took almost two decades for the fabrication technology to move from expensive botique manufacture to industrial strength mass production. Today this technology is being put into cellphones, broadcast satellite receivers and TV sets. The author recalls a development project in 1984 where he has not permitted to use a GaAs low noise transistor in a $100k piece of high speed communications equipment - too expensive, Carlo, find a cheaper way to do this!. A decade ago the GaAs component market was dominated by military buys, which today comprise only around 2% of the total market volume.

The problems in producing a digitally controlled solid state AESA were evident very early - cost, density and power handling would be critical. All of these factors have contributed to the relatively late deployment of the technology in operational aircraft.

The basic building block of any AESA is the Transmit Receive Module or TR Module. It is a self contained package making up one AESA antenna element, and contains a low noise receiver, power amplifier, and digitally controlled phase/delay and gain elements. Digital control of the module transmit/receive gain and timing permits the design of an antenna with not only beam steering agility, but also extremely low sidelobes in comparison with passive ESA and mechanically steered antennas.

Two other important benefits are derived from this design approach. The first is an very important improvement in antenna noise behaviour, since the TR module's low noise receiver is within the antenna itself. Typically this yields between a two and fourfold reduction in receiver thermal noise, in turn contributing to improved radar sensitivity and thus detection range, all else being equal.

The second important benefit is a result of the transmitter power stages being distributed across hundreds or over a thousand TR modules, rather than being concentrated into a single transmitter tube. As a result, failure of up to 10% of the TR modules in an AESA will not cause the loss of the antenna function, but merely degrade its performance. From a reliability and support perspective, this graceful degradation effect is invaluable. A radar which has lost several TR modules can continue to be operated until scheduled downtime is organised to swap the antenna. Other beneifts also accrue - a classical design with a high power tube must carry the transmitter power to the antenna through a pressurised waveguide, and power will be lost in the antenna. Transmitter tubes require highly stressed high voltage high power supplies, which also tend to be unreliable. Since each TR module only handles several Watts of power, fed from a low voltage supply (several Volts rather than kiloVolts), it can be designed for much lower electrical stress levels.

As a benchmark, typical conventional fighter radars have Mean Times Between Failure (MTBF) of around 60 to 300 hours - AESA radars push the MTBF into the 1,000 hours or better class. Rather than several repairs annually to the radar, the AESA will see the radar needing repair only once every several years of operation. If we assume an annual flying rate of around 200 hours, on average the AESA needs to be repaired once every five years! From a support costs perspective, this means much reduced cost of ownership for fighter fleet operators who transition to the technology.

An AESA becomes a combined transmitter, low noise receiver and beamsteering package, providing high beamsteering agility, very low radar signature when illuminated and extremely low sidelobes, all digitally controlled. With digital control of TR module gain, power management which is vital for reduced or low probability of intercept (RPI, LPI) operation becomes relatively easy to do. Beamsteering agility also facilitates reduced or low probability of intercept scan patterns.

In many respects an AESA is a fighter radar designer's dream device, since it not only vastly improves performance and functional capabilities, but does so with improved reliability and complete digital control of antenna/transmitter functions. Over the life of an AESA radar, progressive refinements in many aspects of antenna behaviour can be incorporated through incremental software upgrades. Software programmable AESAs at this time largely implement digital equivalents of established antenna beam shapes, scan patterns and sidelobe behaviours. Over time with proper intellectual effort, further improvements are possible.

Are there any drawbacks to the AESA? Two issues are of key importance with this technology.

The first item of interest is power dissipation. Due to the behaviour of microwave transistor amplifiers, the power efficiency of a TR module transmitter is typically less than 45%. As a result, an AESA will dissipate a lot of heat which must be extracted to prevent the transmitter chips becoming molten pools of Gallium Arsenide - reliability of GaAs MMIC chips improves the cooler they are run. Traditional air cooling used in most established avionic hardware is ill suited to the high packaging density of an AESA, as a result of which modern AESAs are liquid cooled. US designs employ a polyalphaolefin (PAO) coolant similar to a synthetic hydraulic fluid. A typical liquid cooling system will use pumps to drive the coolant through channels in the antenna, and then route it to a heat exchanger. That might be an air cooled core (radiator style) or an immersed heat exchanger in a fuel tank - with a second liquid cooling loop to dump heat from the fuel tank. In comparison with a conventional air cooled fighter radar, the AESA will be more reliable but will require more electrical power and more cooling, and typically can produce much higher transmit power if needed for greater target detection range performance (increasing transmitted power has the drawback of increasing the footprint over which a hostile ESM or RWR can detect the radar).

Another issue of concern with AESAs is the mass production cost of the TR modules. With a fighter radar requiring typically between 1,000 and 1,800 modules, the cost of the AESA skyrockets unless the modules cost hundreds of dollars each. With early module builds yielding unit costs of around USD 2,000 the cost penalty of using an AESA over a conventional design was prohibitive. The good news in this respect is that the ongoing trend has been downward, in a large part as the production engineering of the modules and MMIC chips has improved. Having an enormous commercial market for similar MMIC chips has yielded important benefits.

The longer term technology trends for AESAs are clear - a progressive cost reduction as volumes increase and production matures, with concurrent refinements in digital antenna control techniques improving the capabilities of the antennas.

At this time the US are leading the pack by a large margin in AESA technology, with the EU and Israelis trailing. The Russians remain in the passive AESA domain but this will change as commercially available GaAs MMICs proliferate. The Russians have a robust track record in passive ESA design and the only obstacle to an AESA equipped Su-30M is the availability of suitable chips in volume.

Current AESA Programs

A number of AESA programs are currently under way, some as new build radars for new fighter designs, some as retrofits to existing aircraft.

The first generation of AESAs to field will be the L-band (decimetric) radars used in the Israeli Phalcon derivatives, and importantly the RAAF's Wedgetail MESA radar which is expected to be used in the new USAF MC2A (Multi-sensor Command Control Aircraft) E-3 AWACS, E-8 JSTARS, RC-135 Rivet Joint replacement. The lower L-band operating frequency of these radars permits the use of older transistor technology, giving this class of AESA about 5 years of market lead against the X-band fighter AESAs.

The E-8 JSTARS is a candidate for an X-band AESA replacement of its existing passive ESA radar, used for high resolution mapping and surface target detection. It is likely that the planned JSTARS AESA will be used on the MC2A - the MC2A variant to be used to replace the JSTARS/AWACS combo will be a 767 airframe carrying both radars (this is a potential growth path for the Wedgetail, by the addition of a JSTARS/MC2A derivative radar under the forward fuselage).

US sources indicate that the RQ-4 Global Hawk is likely to see an AESA upgrade later in the decade, to provide increased range and radar optimisations for accurate ground target tracking, and airborne target tracking


In the fighter domain the first AESA to field is the AN/APG-63(V)2 on the F-15C. This is a major upgrade of the original AN/APG-63 radar using a 1500 element AESA. While only 18 F-15Cs were originally to be retrofitted, the gains in reliability and thus reduced support costs are likely to see this AESA migrate onto the USAF's 200+ strong F-15E fleet, as well as further F-15Cs. The Korean F-15K is expected to carry this AESA, making it the most capable fighter in the Asia-Pacific region.

The next AESA to field will be the Northrop-Grumman AN/APG-77 radar on the USAF's F-22A. This 1,500 element AESA will remain the highest performing fighter radar in the market for the forseeable future. Designed with a very low radar signature antenna, it will provide the F-22 with a greater detection and engagement range than any other fighter in the market. Current planning envisages that the -77 will transition from the current TR module design to a design common to the F-35 JSF radar, with the aim of cost reductions. Recent US disclosures suggest that this will happen around the middle of the decade, as an F-22A Block 5 configuration, with the AESA rework incorporating antenna features for undisclosed advanced ground attack modes. The AN/APG-77 radar is the first of new generation of radars which push the back end signal and data processing functions into the aircraft's central computers, rather than inside a dedicated radar processor box.

The third AESA to field will be the 1,000 element Northrop-Grumman AN/APG-80, formerly the AN/APG-68 Agile Beam Radar, on the UAE's new F-16C Block 60 fighter. This radar is a substantial redesign of the established AN/APG-68 and will utilise COTS VMEbus derived high performance processing in the radar back end functions. It is expected to support not only the full range of air-air and strike modes, but also interleaved terrain following. IOC is likely to be in the 2003-2004 timeframe.


The fourth AESA to field is likely to be the 1,100 element Raytheon AN/APG-79, formerly AN/APG-73 RUG III, on the USN's new F/A-18E/F fleet. This AESA is a block upgrade to the existing AN/APG-73 series. Whether the whole F/A-18E/F fleet receives the radar has not been disclosed, but given the longer term life cycle cost benefits this could become a long term priority for the USN.

The F-35 JSF, if it proceeds to plan, will field with a 1,200 element AESA radar using a similar architecture to the F-22's AN/APG-77. While little has been disclosed in the way of design details, this radar is likely to resemble a scaled down and less capable F-22 radar, with a strong optimisation for strike roles.

Other players are entering the market. Work continues on the European AMSAR AESA for the Eurofighter Typhoon. Public data suggests a 1,500 element design although this might be optimistic given the size of the Typhoon. An AMSAR derivative is a likely retrofit option for the Rafale.

Israel's Elta has published datasheets on a range of X-band GaAs MMIC chips which would be suitable for an AESA but as yet no disclosures of system level products have been made.

Reports also suggest that the Russian radar houses are working on AESA designs, although details remain very sketchy. Any Russian design would have to make use of imported GaAs MMIC chips as Russia's industry lags severely in this area. A likely outcome is that COTS GaAs MMICs would be adapted for a Russian design, as the export controls on high volume X-band satellite transceiver chips are likely to be unenforcable over the coming decade. A suitcase of GaAs MMIC chips makes for a lot of AESAs.

It is not inconceivable that we may see a robust number of AESA retrofits over the coming decade to established teen series fighter fleets in the West, as the investment in this technology returns a large payback in medium and long term support cost reductions. With large fleets of the F-15C/E and F-16C in USAF and export client service, possibly several hundred aircraft could be retrofit candidates.

What impact does the AESA have for Australia? Clearly any aircraft considered for A6K must have an AESA - anything less is simply an unnecessary drain on fighter support budgets.

In terms of retrofits, the remaining life cycle and increasing strategic irrelevance of the F/A-18A HUG make it a poor candidate for an AN/APG-79 AESA retrofit later in the decade. The F-111 would be an excellent AESA retrofit candidate especially since the support cost reductions and reliability gains over the 1960s AN/APQ-169/171 suite would achieve a major impact in life cycle costs in the 2015-2020 timescale. As recent testimony by LtGen Mueller to a parliamentary committee indicates, the principal issue in F-111 life-of-type will be the support of the remaining 1960s generation aircraft systems in the post 2010 period, given that the RAAF is now retrofitting AMARC F-111F wings to gain significantly more airframe fatigue life.

Current trends are that the AESA will supplant conventional mechanically steered radars in all production fighter applications over the coming decade, and there are good prospects for partial fleet retrofits across the several thousand teen series fighters likely to remain in service over the next 2-3 decades. The only issue with the AESA will be securing near term funding for retrofits, given that the support cost payback may take several years to be seen. Given the tremendous combat capability gains resulting from the AESA, the case for retrofits is very robust if the aircraft is to remain in service for more than a decade.

In summary, the AESA will have a revolutionary impact over the coming decade, and smart players should be now exploring how to best exploit this pivotal technological development.

(http://www.ausairpower.net/aesa-intro.html)

Without doubt the most important development in microwave technology during the last decade has been the Monolithic Microwave Integrated Circuit (MMIC). The MMIC is to the RF engineer what the integrated logic gate was to the computer engineer, decades ago - the means of building complex designs with economical prepackaged functional blocks. In this month's feature we will take a closer look at the MMIC and its implications for microwave and digital communications over the coming years.

RF Design Issues

Designing analogue hardware to operate at radio frequencies (RF) has traditionally been a relatively messy process, in comparison with digital logic design, and remains very much the domain of a very specialised community of engineers. RF hardware is by its basic nature analogue, and few opportunities existed in the past practice of the design process to abstract functional blocks and avoid the frequently pathological behaviour of component level designs.

Let us consider a sixties or seventies RF design such as a low noise preamplifier used in a receiver. The available component base comprised primarily Silicon and Germanium bipolar transistors, axial lead resistors and capacitors, and ferrite and air core inductors.

Each and every one of these components exhibits parasitic or stray capacitance, inductance and in the transistors, internal capacitances resulting from the geometry of the transistor die, and the behaviour of the semiconductor junctions.

A design engineer would therefore construct a fairly elaborate mathematical model for the intended circuit's behaviour in the RF domain, and concurrently would also have to do the same for the direct current (DC) behaviour of the circuit to ensure that the transistor was operating in the intended regime and was stable with varying temperature. To complicate things, a noise performance model was also required, to account for the thermal noise in resistors and shot noise in the transistor. Of course, calculations or simulations would also be required to account for component tolerances, since RF transistor specs would be very loose, and 1% accurate resistors rather expensive.

Through repeated iterations using a calculator, or if paid for by a serious employer, a software simulator like SPICE, the engineer would zero in on the intended combination of component values to get the right balance between gain performance, noise performance and thermal stability, while looking over his shoulder for the company accountant, heard mostly complaining about project delays and extravagant choices in transistors and capacitors.

Once the theoretical design was completed, a prototype would be fabricated on a printed circuit board and tested. No chance of delegating the printed circuit board layout to a draftsman since the oddities of RF require that the primary designer produce the layout him- or herself.

Usually the prototype would oscillate due to feedback coupling at radio frequencies, and would require revisions to the board layout and judicious adjustments in component values, mostly determined empirically yet again through multiple iterations. Finally a working prototype existed.

The next phase in the process was a demonstration production unit, built to the documentation package in a production environment and carefully tested to verify its performance. More than often further iterations would follow.

Finally, the design would be transfered to production, and would usually require manual adjustment by a technician to exactly meet the intended specification. Very careful and accurate assembly was mandatory, to ensure that parasitic inductances and capacitances were not inadvertently added into the design by cutting component leads to the wrong length, or putting a bend in the wrong spot.

Was this messy ? Absolutely !

Classical RF design and manufacture was time consuming in every respect, during every portion of the process from idea to end product. Increasing the operating frequency from the HF, VHF to UHF was a headache, and going microwave a nightmare. At microwave frequencies, even tiny stray capacitances of nanoFarads and inductances of nanoHenries could wreak havoc with a design. Moreover, shielding covers or cavities to contain the circuit would contribute.

Perhaps the biggest headache of all was reproducibility in designs, since the combination of sloppy component tolerances and mechanical assembly left many opportunities for designs to deviate from the intended specification.

By the seventies RF designers with the budget to do so shifted from printed circuits to hybrid circuits, using ceramic substrates with resistors, capacitors and conductors fired on to the surface of the ceramic substrate, and active components such as transistors and diodes then soldered on to the substrate.

"Hybrids" proved to be excellent, since they allowed much more compact physical designs, and tighter production tolerances. Cost however remained a major issue, as a result of which hybrids became a staple item in equipment like radars but continued to be a cost problem for commercial and consumer equipment.

Another issue which proved to be an ongoing problem was the performance of transistors with increasing frequencies. Silicon bipolar transistors, the workhorse of the digital logic base, would suffer worsening gain problems at several GigaHertz and were frequently also noisy. While speed could be improved to a large degree by shrinking the size of the transistor, a more subtle problem arose, which was inherent in the Silicon material itself - poor electron mobility.

Mobility is a measure of how quickly charge carriers (electrons, holes) can travel in the crystalline lattice when an electric field is applied. The lower the mobility, the stronger the field required to make them move quickly. In a transistor which is trying to amplify a signal at many GigaHertz, poor mobility tranlstaes into poor gain, and gain is the measure of a transistor's worth in most of its uses.

The answer was to be found in GaAs semiconductors, rather than Silicon. GaAs has typically around six times the electron mobility of Silicon, providing the potential for significantly faster transistors. GaAs also proved to be better from a noise performance perspective, so the two key problems in an RF transistor, speed and noisiness, were ostensibly solved by the GaAs transistor.

The reality was not as tidy as was initially expected. It has taken almost two decades for GaAs components to transition from the early production components to today's mature volume products. During my undergraduate years, the standard joke in the EE community was "GaAs - the material of the future - still ...".

The problems with GaAs were manifold. The material proved to be very difficult to fabricate, the transistors proved to be very fragile and easily damaged by electrostatic discharge, overheating or electrical overload, much more so than Silicon. In the employ of one company, I was banned from using a GaAs transistor since it was expected that the production workers could not solder them in without damaging them !

The commercial pressures for more bandwidth grew very rapidly during the early nineties, with the massive growth in mobile telephone use, and the growth in the Internet. Mobile telephony proved to the key volume driver for commercial commodity GaAs components.

However, the technology base for RF could not move ahead while remaining shackled to Silicon integrated circuits and discrete GaAs transistors.

Silicon fabrication techniques allow for digital components which can be clocked well beyond a GigaHertz, and Silicon allows for tremendous density. However, combining density with low noise Silicon bipolar transistors has proven to be difficult, indeed the fastest low noise Si bipolar discretes this writier has seen are only useful to several GigaHertz.

Clearly the answer to this problem was to integrate many GaAs transistors on to a single chip, in the manner performed with Silicon successfully over the last 4 decades. This proved to be no mean feat, given the finicky nature of GaAs as a material. The Microwave Monolithic Integrated Circuit (MMIC - pronounced "mimic") proved to be an elusive goal.

A lot of expensive research was required to push the GaAs transistor from the domain of discretes into the integrated circuit (IC).

Much of the early funding and early production of GaAs ICs was paid for by the US DoD. They had a very strongly vested interest in this respect, since radar remains the key military sensor used for finding things to blow up. Whether we are building radars, or building equipment to jam radars, we require high density, reliable, economical RF building blocks. The particular prize in the military game was a device called an Active Electronically Steered Array (AESA), also known as a "phased array". An AESA is a flat panel microwave antenna which can be pointed by individually manipulating the phase shifts, or delays, of the hundreds or thousands of individual receive and transmit elements which make up the array.

With no moving parts the AESA is very reliable, can point its beam in milliseconds, yet it can be easily buried into the flat surfaces of a stealth fighter or bomber, and can be built with sidelobes 1/100 - 1/1000 the magnitude of a conventional mechanical antenna. The AESA was the radar designer's dream.

The snag with the AESA is that it needs at least 1500 and more typically 2000 individual transmit receive modules, each of which has to contain a transmitter, receiver and phase shifter, as well as the radiating element, digital control bus and RF feed connections. Operating at 10-20 GHz, each much be less than a centimetre in cross section.

Needless to say the only technology which could possibly allow the manufacture of the densely packed AESA TR modules was the GaAs MMIC. The US DoD was the first major player, but quickly followed into the fray by the EU and the Israelis, as well as the Japanese. All funded research and pilot production, and now all are either paying for the manufacture or the impending manufacture of AESAs.

Once the expensive research was done and the production techniques were refined, the manufacturers quickly turned to commercial applications, for which GaAs opened up huge possibilities: mobile telephony, satellite telephony, mobile networking, multipoint distribution, satellite communications. Any application which could benefit from a RF chip using GaAs was a candidate.

The big attraction commercially lies not only in performance, but also board level manufacturing, since economical high volume robotic component placement can be used, and many of the production tolerance problems seen with manual assembly simply go away.

The Silicon monolithic integrated circuit appeared during the sixties and has since then revolutionised the computer industry, as well as the consumer electronics industry. While the GaAs MMIC is a late arrival, it promises similar revolutionary changes in RF technologies, and many cabled high speed digital communications technologies. Silicon will remain competitive in many lower speed RF applications, but the high ground has now been taken by GaAs.

The basic building block in any solid state integrated circuit is the humble transistor, and this is no less true for a GaAs MMIC. The transistor is used as a switch, an amplifier, or if contorted in the right manner, a current source or load resistor.

In Silicon based technologies, the two "workhorse" transistor types are the classical bipolar device, and the MOSFET, a mainstay of high density digital circuits. Neither proved to be practical for GaAs.

The first GaAs transistor to achieve high production volumes, as individual disrete transistors, was the MESFET (Metal Semiconductor Field Effect Transistor).

The MESFET is a close cousin to the Silicon MOSFET, and like the MOSFET, is constructed with a source, gate, and drain (See Figure 1. by Litton). A voltage change between the transistor's gate and source pins causes a change in the current flow between the source and drain pins. Unlike the MOSFET, where the gate is insulated from the semiconductor substrate by an oxide layer, the MESFET uses a Schottky metal junction produced by applying the metal gate electrode to the semiconductor directly.

Unlike Silicon, where a MOSFET can be easily fabricated by doping a source and drain, laying down an oxide for the gate, and then putting down Aluminium connections for tracks, sources, drains and gate electrodes, GaAs MESFETs are much more demanding to build.

The MESFET is fabricated on a GaAs substrate, using Molecular Beam Epitaxy (MBE) techniques to grow extremely thin layers of doped GaAs with precise thicknesses and compositions. The bulk of the MESFET comprises a lightly negatively (N+) doped layer, over which a more heavily doped layer is placed to form a base for the source and drain contacts. Channels are etched into the substrate for the gates, which are then applied as a layered Pt/Ti/Au (Platinum, Titanium, Gold) structure and then carved to an exact trapezoidal shape using an electron beam. The gate is about half a micron in length.

The source and drain contacts are then produced using layered structures of Germanium gold alloy (GeAu), nickel and gold (GeAu/Ni/Au), the Germanium doping the underlying GaAs to improve contact performance.

While the MESFET provided a robust basic device for many applications, especially those involving low noise high speed receivers and buffers, its performance ceased to be competitive with the advent of more complex High Electron Mobility (HEMT) transistors. MESFETs do remain widely used, and are especially common in applications such as switches and attenuators.

The HEMT (Figure 2. - Litton) transistor family spans a range of devices, with manufacturers frequently using variations on the nomenclature to label their proprietary flavour of the device.

Where HEMTs differ from older MESFET devices is in the use of heterostructures, in which two different semiconductors are used to form the transistor. While any meaningful discussion of the solid state physics of GaAs HEMTs would exceed the scope of this treatment, suffice to say that the heterojunction layer between the AlGaAs and InGaAs creates conditions in which an electron gas with very high mobility is formed. As a result the transistor is significantly faster than the classical MESFET, which relies on the mobility performance of the base material alone.

Pseudomorphic HEMTs (PHEMTS) are available with useful performance out to many tens of GigaHertz.


(Image - Lockheed-Martin)


(Image - Siemens)

GaAs MMICs

The step from the fabrication of individual transistors to complete monolithic circuits with tens to hundreds of components on a single slab of GaAs has its complexities. While the techniques for processing the materials are essentially the same, quality demands do go up since losing one transistor out of a hundred due to a fabrication defect amounts to losing a whole chip die if you are fabricating a a wafer of MMICs.

The other significant issue with MMICs is the development of design rules for the layout of components and connections, and the development of robust passive components such as PIN diodes, resistors, capacitors and inductors which may be integrated into the same slab of GaAs. Since the MMIC is a complete microwave RF circuit on a chip, the design must reflect established RF design rules.

The density of a GaAs (or Si) MMIC is much lower than that of competitive Silicon digital ICs, even if similar transistor sizes are used, simply because of the need to observe the same RF design rules which plagued RF circuit designers in decades past. Every track is a waveguide ....

An example of a 60 GHz satcom power amplifier MMIC with a 550 mW output rating (Lockheed Martin, Chao et al.) is depicted in Figure 3, and a GSM MMIC (Siemens, Kapusta) is depicted in Figure 4. Lower operating frequencies do allow some increases in density, but millimetric band operation usually allows no compromises.

The great enabler for MMIC design has been the availability of cheap compute power and excellent simulation software, which allows engineers to devise circuits using previously tested structures and frequently also building blocks.

A very wide range of GaAs MMICs are now available in the commercial marketplace, many of which are general purpose building blocks, some of which are versions of radar and AESA components, and increasingly, custom devices for established commercial applications. These devices can be supplied as dies alone for use in multichip modules or hybrids, or in conventional resin TSSOP or SSOP28 packages for robotic surface mount on printed circuit boards.

For a product designer working at the board level, a suitable range of of-the-shelf MMICs allows the rapid design and development of RF equipment with a minimum of fuss, since the most difficult bits are hidden away in the MMIC. What we are seeing today in RF design is what happened in logic design two decades ago, when MSI chips largely changed the game.

Clearly the market for GaAs MMICs is booming, between 1997 and 1998 a 200-300% growth in deliveries was observed. Manufacturers are now aiming at maximising volumes and minimising costs, and have shifted from 4 inch wafers to 6 inch wafers. Cost still remains an issue in comparison with Silicon, since the equipment for molecular beam epitaxy and electron beam shaping is extremely expensive, and the cost of the raw materials is also much higher. Typically the cost of a 4" GaAs MMIC wafer is simlar to that of a 6" Si MMIC wafer.

Market projections for this year indicate that the primary uses of GaAs MMICs, in descending order of volume, will be TV / Cable TV tuners/modems, and mobile telephones, both with about 45% of the total market volume, followed by wireless LANs with about 5% of market volume, and automotive distance warning radars with about 0.5% of market volume. Military radar and satellite comms, which were the original targets of the basic research effort, amount to about 0.25% of the market collectively.

If current trends continue, we can expect to see an ongoing decline in costs and broadening uses of GaAs MMIC technology in consumer and commercial applications. The technology will contribute to further growth in other areas, such as high speed networking and wireless networking.

Like the Internet, the GaAs MMIC was born out of the military research base yet is likely to produce its greatest impact in commercial and consumer markets. An interesting point to ponder!




(http://www.ausairpower.net/AC-0700.html)

Agile radar beams
Active electronically scanned arrays energize fighter performance
By Michael Peck and Glenn W. Goodman Jr.
May 09, 2005
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Advanced digital radar systems are giving new U.S. fighter planes the unprecendented ability to search for aircraft, track ground vehicles and map terrain simultaneously — at greater ranges and with better reliability than conventional systems.

Key to the capabilities in the new systems, called active electronically scanned array (AESA) radars, is an antenna consisting of 500 to 1,000 transmit/receive (T/R) modules, each the size of a candy bar or even smaller, instead of a central transmitter and receiver. Each module acts like a small individual radar.

Unlike a conventional mechanically steered array (MSA), the antenna array of T/R modules is fixed, with no moving parts. The radar can steer its agile beams electronically — at nearly the speed of light — and redirect them instantaneously from one target to another.

n MSA radars, a circular or elliptical antenna plate in the nose of the aircraft is moved rapidly using a gimbal system with three or four drive motors to scan an area of airspace or on the ground, a single flashlight-like beam at a time. AESA radars can track significantly more targets than current mechanical systems and can operate in multiple modes simultaneously, such as air-to-air search and ground mapping.

The first AESA radar that will be produced in large numbers for a fighter aircraft is Raytheon’s APG-79, slated to become operational on new U.S. Navy single-seat F/A-18E and two-seat F/A-18F Super Hornets in September 2006. It will offer up to three times the aerial target detection range and five times the reliability at only about 40 percent of the operating and support costs of Raytheon’s predecessor APG-73 radar on F/A-18C/D Hornets and those Super Hornets already produced, the company says. AESA radars also are being developed by Northrop Grumman Electronic Systems in Baltimore for the U.S. Air Force’s new F/A-22 Raptor and the planned Joint Strike Fighter.

PASSIVE VS. ACTIVE

Electronically scanned array antennas have been around since the 1950s in land-based and shipboard radar applications, but were slow to take hold in airborne applications due to volume and cost constraints.

Passive ESA radars, such as the U.S. Army’s Patriot and U.S. Navy’s Aegis, use a central transmitter and receiver like MSAs to feed their radiating elements, but steer the beam using an electronically controlled phase shifter placed immediately behind each radiating element. In the AESA radar, a small, low-power T/R module is placed immediately behind each radiating element, eliminating the central transmitter and receiver and the signal power losses that occur in the passive ESAs when the central transmitter distributes signals to the radiating elements and return signals are combined in analog form and sent to the central receiver. Historically, the central (traveling wave tube) transmitter and its high-voltage power supply have accounted for a large percentage of failures experienced in airborne radars.

Both passive and active ESAs offer higher reliability than MSAs because of their lack of moving parts and the fact that the phase shifters in the passive ESAs and the T/R modules in AESAs are inherently reliable. In addition, as many as 6 percent of the phase shifters or the T/R modules can fail without seriously impairing the radars’ overall performance. Both passive and active ESAs also offer more agile beam steering. For example, to jump the antenna beam from one target to another separated by 100 degrees, an MSA takes roughly a second. An ESA can do it in less than a millisecond. An AESA can even simultaneously radiate multiple, independently steered beams on different frequencies.
Aircraft that use passive ESA radars include the U.S. Air Force’s B-1B bomber and E-8 Joint Surveillance Target Attack Radar System and the French Rafale fighter.

Breakthroughs in T/R module manufacturing and miniaturization in recent years — Northrop Grumman and Raytheon use what they call sixth-generation T/R module technology — at last have made it feasible to fit large numbers of the modules in a lightweight AESA antenna in the nose of a fighter aircraft.

“To populate a radar with many hundreds of these T/R modules and getting them to act together is revolutionary. In fact, taking all the moving parts out of airborne radars is revolutionary,” said Scott Porter, director of aerospace business development at Northrop Grumman-Baltimore.

“For the same amount of real estate on an aircraft, especially fighters, you can cram a lot more of the T/R modules into an antenna and fill up more of the aircraft than you can with an MSA. Instead of one moving antenna with a transmitter black box behind it trying to pump out power, you now have many, many T/R modules mounted together in the same space all staring at the same place at the same time.”

AESA life-cycle costs are expected to be significantly lower than those of MSAs, Porter said, because their electronics will be more reliable and easier to fix than the moving parts in an MSA assembly. Indeed, Northrop Grumman is so confident in the reliability of the Joint Strike Fighter’s APG-81 radar that it may recommend that the nose radome be sealed. Though this would make it harder to repair the system, Northrop Grumman engineers say the radar will function properly for years, and that it could lose up to 6 percent of its T/R modules without affecting performance. “We don’t expect many radomes to be removed after our AESA radars are installed,” Porter said.

Similarly, Raytheon says the mean time between critical failures of its APG-79 radar going on the Navy’s Super Hornets is in excess of 15,000 hours of operation, and claims its AESA antenna might require no maintenance for 10 to 20 years.


FIRST OF THEIR KIND


The only operational fighter aircraft currently equipped with an AESA radar are 18 U.S. Air Force F-15Cs with the 3rd Fighter Wing at Elmendorf Air Force Base, Alaska. They have flown for about five years with the APG-63(V)2 developed by Raytheon Space and Airborne Systems, El Segundo, Calif. That radar, no more of which will be built, is a predecessor to the company’s more advanced Navy APG-79. It was an AESA antenna upgrade to the F-15’s APG-63(V)1 MSA radar designed to add a capability to target small cruise missile-size targets. The APG-63(V)1 MSA remains in full-rate production.

Raytheon has been developing a lighter-weight, more maintainable AESA radar for the Air Force’s other 161 F-15Cs — the APG-63(V)3 — and has built a prototype that will be tested by the service. However, due to budget constraints, those aircraft may never get the upgrade. The Air Force firmly plans to modernize the MSA radar on its 224 newer F-15E ground-attack models, beginning around 2010, likely with an APG-63(V)4 radar from Raytheon that will use the AESA antenna from the (V)3, as well as processors from the Navy’s APG-79.

Drawing on APG-79 technology, the (V)3 AESA uses more compact “tile” T/R modules compared with the (V)2’s larger “brick” modules. The tiles reduce the number of required T/R modules by a factor of four and the depth of the antenna array from nine inches to four inches, said Michael Henchey, Raytheon’s director of strategy and business development for Air Combat Avionics. They also reduce the weight of the array significantly.

Raytheon, following a year of flight testing, began delivering the first low-rate initial production versions of the APG-79 in January to F/A-18 manufacturer Boeing Integrated Defense Systems, St. Louis. The radar is a key element of Block II upgrades preplanned for the Navy’s Super Hornets, which became operational in 2001. The service will conduct operational testing of the LRIP radars on Super Hornets in October and November. Full-rate production of 415 APG-79s is scheduled to begin in 2007.

Bill Gardner, Raytheon’s APG-79 engineering, manufacturing and development program manager, said the radar will detect and track twice as many targets at greater distances than the APG-73, permitting the aircrew to “persistently observe targets and launch air-to-air missiles from their maximum range.” The radar system automatically establishes tracking files for each detected target, reducing pilot workload.

Another key feature of the APG-79 will be its ability to conduct air-to-air and air-to-ground operations essentially simultaneously because it can switch modes so rapidly. The pilot will be able to conduct ground mapping with the radar while it continues searching for and tracking aerial targets.
“With interleaved air-to-air and air-to-surface cockpit displays, the aircrew will be able to maintain situational awareness while executing air-to-surface missions,” Gardner said.

AESA radars also offer better air-to-ground resolution than MSA systems, particularly using their synthetic aperture radar (SAR) mode. As a March 2004 Government Accountability Office report stated, “The first F/A-18F with the AESA radar installed recently demonstrated high-resolution SAR modes at three times the resolution and 2½ times the range of the currently operationally deployed F/A-18 radar. This capability represents the first step in multiple areas that the AESA radar will greatly improve the F/A-18E/F Super Hornet’s air-to-air and air-to-ground radar capabilities in addition to adding modes not currently available to the fleet.”


OTHER AESA RADARS


Early this year, Northrop Grumman-Baltimore delivered the first APG-81 AESA radar for the Lockheed Martin F-35 Joint Strike Fighter. It is undergoing development flight tests onboard Northrop Grumman’s BAC 1-11 flying test-bed aircraft. Late this year, the radar will go to Lockheed Martin’s Mission Systems Integration Lab for testing to integrate it with the rest of the mission systems suite.

A joint venture of Northrop Grumman-Baltimore and Raytheon Network-Centric Systems, McKinney, Texas, has been developing the APG-77 AESA radar for the F/A-22 fighter for nearly 15 years. The radar flew on a preproduction aircraft for the first time in late 2000. Its T/R modules have been improved over time, and software allowing the radar to perform high-resolution mapping of ground targets is being added.

A fourth-generation variant of the APG-77, with design improvements adapted from the APG-81, flew for the first time last June. “We are inserting our fourth-generation AESA technology into the F/A-22’s Lot 5 of production, and that radar is in flight-test now,” Porter said. “So the F-35 and F/A-22 will have highly common radars at that point.” Pentagon officials approved the F/A-22 for full production at the end of March; the fighter will become operational in December.

AESA radars also have been in development for the three latest European fighters — Sweden’s JAS-39 Gripen, the Eurofighter Typhoon and France’s Rafale. The Gripen and the Eurofighter are equipped with mechanically steered array radars, and Rafale with a passive electronically scanned array, each of which features air-to-air and air-to-ground modes.
The Swedish Air Force’s Saab-built Gripen, also being acquired by South Africa, the Czech Republic and Hungary, became operational in 1997. It carries the PS-05/A radar from Ericsson Microwave Systems, which has been developing an AESA radar to potentially replace the PS-05/A.

Germany, the United Kingdom, Italy and Spain are the four Eurofighter partner countries. Development of the aircraft’s ECR-90 Captor radar by the EuroRadar consortium (BAE Systems, EADS, Spain’s INISEL and Italy’s FIAR) began in 1990; the radar entered production in 1998. Delivery of the first 148 Tranche (Lot) 1 production aircraft, begun in 2003, will be completed in 2007. Production of 236 improved Tranche 2 aircraft with upgraded computers was set to commence soon, and negotiations have been in progress among the partner countries to define the capabilities package for the 236-aircraft Tranche 3.

France’s Dassault is in series production of carrier-based Rafale M and air force Rafale B/C variants for the French military. They carry the RBE2 passive electronically scanning array radar developed by Thales DETEXIS.
In 1993, a BAE Systems-Thales-EADS consortium began development of a new AESA radar to replace the Eurofighter’s ECR-90 and the Rafale’s RBE2. Called the Airborne Multi-mode Solid-state Active array Radar , it could be ready for fielding on Tranche 3 Eurofighters and Rafales around 2010.

For electronics companies accustomed to building conventional MSA radars, fabricating AESA systems presents challenges. “We’ve built MSAs with the same building blocks for the past 30 or 40 years,” Porter said. “To design and manufacture an AESA radar is a totally different process.”

Porter said he foresees AESA systems being simpler to maintain in the future, with ground crews able to replace individual T/R modules without having to remove the entire radar assembly from the aircraft. He also said he sees aircraft radar evolving to the point where it is built directly into the skin of the aircraft.

“You can develop radar antenna arrays that can be structurally incorporated into the skin of an aircraft. However, such ‘smart skin’ would have to be an integral part of the design from the very beginning,” Porter said. “It would be tough to get all those T/R modules to stare at the same space. And remember that instead of the radar being nice and snug inside a radome, it would be exposed to the elements.”

(http://www.c4isrjournal.com/story.php?F=750341)

• Northrop Grumman/Raytheon AN/APG-77, for the F/A-22 Raptor.
• Northrop Grumman AN/APG-81 for the Joint Strike Fighter
• Raytheon AN/APG-63(V)2 and AN/APG-63(V)3, for the F-15C Eagle.
• Raytheon AN/APG-79, for the F/A-18E/F Super Hornet.
• Raytheon AN/APG-80, for the F-16E/F Block 60 Fighting Falcon

• APG-77 125nm/200km against a 1m2 in LPI 2,000 TR modules
• APG-81 85nm/137km 1,200 T/R modules
• APG-63v2 80nm/129km 1,500 T/R modules
• APG-79 70nm/113km ~1,100 T/R modules

The AN/APG-77 is an active electronically-scanned radar designed for the F/A-22 Raptor fighter aircraft. It features separate transmitter and receiver for each of the antenna's radiating elements to provide the agility, low radar cross section and wide bandwidth requested for the F/A-22.

The APG-77 will be more reliable, easy to repair, and maintainable than currently fielded aircraft radars through the use of solid state technology and elimination of mechanical moving parts. Originally, the APG-77 was designed to carry out only air-to-air engagements but emerging threats, US military transformation and latest weaponry have made desirable the F/A-22 to assume strike missions.

The fourth generation variant of AN/APG-77 electronically scanned array radar system features reduced production and maintenance costs compared to third-generation variant. The APG-77 new design has been previously implemented successfully in the APG-80 (F-16E/F) and APG-81 (F-35) radars.

The AN/APG-77(V)4 radar requires fewer parts than previous variants and its production line relies on a greater degree of automation. A new software being developed by Northrop-Grumman will enable high-resolution mapping of ground targets. This will permit all-weather precision strikes.

According to Northrop-Grumman estimates, the Pentagon would order 203 fourth-generation APG-77s including retrofit kits for third-generation APG-77 radars already delivered and in service on operational F/A-22s.

On 25 May 2005, Northrop-Grumman delivered the next-generation APG-77 named the AN/APG-77(V)1 AESA (Active Electronically Scanned Array) fire control radar. This radar set was scheduled for testing in the summer 2005 at Edwards Air Force Base, California. APG-77(V)1 variant, fitted with a new software suite, introduces air-to-ground capability compared with previous models. The (V)1 model production was cheaper thanks to rely on a highly automated production line. The new software suite related to the (V)1 is expected to enable electronic warfare, attack of fixed and stationary targets on the ground and in all-weather day/night conditions. The new radar variant also captured some advances made in AESA design for the F-35 (APG-81) and Block 60 F-16E/F (APG-80).

The AN/APG-81 is an advanced fire control radar being developed by Northrop-Grumman for the F-35 Joint Strike Fighter (JSF). It features air and surface modes and Active Electronically Scanned Array (AESA) antenna for enhanced performance.

The APG-81 radar is under rooftop integration range-testing phase. Early in 2005, it will enter flight testing on a Northrop-Grumman BAC 1-11 testbed aircraft. The BAC 1-11 will test its air and surface modes. In late 2005, the first AN/APG-81 radar system will be delivered to Lockheed-Martin for integration on the F-35 multirole aircraft.

Northrop-Grumman handed over the first AN/APG-81 active electronically scanned array (AESA) fire control radar to F-35 Joint Strike Fighter (JSF) prime contractor Lockheed-Martin on March 3, 2005. APG-81 radar system will support air-to-air, air-to-surface and electronic warfare modes providing the pilot with all-weather precision targeting and advanced air-to-ground automatic target cueing.

The APG-63 radar system combines long range acquisition and attack capabilities with automatic features to provide the instant information and computations required during air-to-air and air-to-surface engagements. It was the first airborne radar system to incorporate software programmable signal processor. That means APG-63s software can be upgraded without replacing the hardware. APG-63 radars are installed on F-15A/B and early F-15C/D aircraft.

The AN/APG-63(V)2 is a major radar upgrade for the US Air Force F-15C aircraft. This upgrade will add AESA (Active Electronically Scanned Array) capabilities to the proven APG-63 radar. AESA technology will increase F-15C's combat performance, while enhancing reliability and maintainability. The promising AESA technology is being developed for the fifth generation fighters like the F/A-22 Raptor.

The AN/APG-79 is an Active Electronically Scanned Array (AESA) developed by the Raytheon company for the F/A-18E/F Super Hornet. The APG-79 will provide superior air-to-air and air-to-surface capability while increasing aircraft's situational awareness. In the air-to-air role the APG-79 will provide longer range engagements and reduced pilot workload. In air-to-surface missions the APG-79 will provide enhanced precision attack through high resolution ground mapping at long standoff ranges.

The APG-79 is composed of a numerous solid state transmit and receive modules to virtually eliminate mechanical breakdown, an advanced receiver/exciter, COTS processor and power supplies. These features characterize the APG-79 radar as a highly reliable radar with reduced operation costs. The Flight tests of the APG-79 radar are scheduled to begin in June 2003. The US Navy plans to buy up to 411 APG-79 radars and some F/A-18s foreign customers could be interested in purchasing this advanced radar.

The new AESA radar system will contribute to the US Navy Network Centric Warfare vision providing the target information which will be distributed to multiple users that, eventually, may engage the target. Operational evaluation is scheduled by September 2006. The first deployment installed on combat ready Super Hornets is expected in 2007.

AN/APG-79 radar systems will be supplied to F/A-18E/F Super Hornets as part of Super Hornet program Block II upgrade. The US Navy's EA-18G Electronic Attack aircraft will be equipped with the APG-79 AESA radar system too.

Raytheon delivered the first low rate production APG-79 radar set to Boeing Integrated Defense Systems in Saint Louis on January 13, 2005. Up to 415 radar sets are expected to follow the first one to outfit US Navy's Super Hornets beginning in September 2006.

On 28 June 2005, Boeing awarded Raytheon a $580 million multi year procurement contract for 190 APG-79 radars to equip the US Navy's F/A-18E/F and EA-18G aircraft. The five year contract included low rate production lot 3 and 4 as well as full rate production lot 1 to 3 with final deliveries expected by 2010.

The AN/APG-80 is an agile beam radar designed for the F-16C/D Desert Falcon Block 60 fighter aircraft ordered by the United Arab Emirates. It features an active electronically scanned antenna.

Source - Defence Annual Report 2002-03

• 192 NM (355 km) Vs that of a 10m2 class target (F-15, Su-27, SU-31MKI)
• 108-125 NM (200 km) Vs that of a 1m2 (New USAF Standard) class target (F-16, MIG-29 SMT)
• 61 NM (113 km) Vs that of a 0.1m2 class target (F/A-18 E/F/G, EF-2000, Rafale B/C/M, Cruise missles)
• 35 NM (65 km) Vs that of a 0.01m2 class target (F/A-18 E/F Block3?, Rafale D?, PAK-FA?, Stealthy cruise missies)
• 20 NM (37 km) Vs that of a 0.001m2 class target (F-35 A/B/C)
• g. 12 NM(22 km) Vs that of a 0.0001m2 class target (F-22A, B2, F117A)

• 148 NM (275 km) Vs that of a 10m2 class target (F-15, Su-27, SU-31MKI) 7
• 83 NM (154 km) Vs that of a 1m2 (New USAF Standard) class target (F-16, MIG-29 SMT)
• 47 NM (87 km) Vs that of a 0.1m2 class target (F/A-18 E/F/G, EF-2000, Rafale B/C/M, Cruise missles)
• 26 NM (48 km) Vs that of a 0.01m2 class target (F/A-18 E/F Block3?, Rafale D?, PAK-FA?, Stealthy cruise missies)
• 15 NM (28 km) Vs that of a 0.001m2 class target (F-35 A/B/C)
• 9 NM (17 km) Vs that of a 0.0001m2 class target (F-22A, B2,)

• 140 NM (260 km) Vs that of a 10m2 class target (F-15, Su-27, SU-31MKI)
• 78 NM (145 km) Vs that of a 1m2 (New USAF Standard) class target (F-16, MIG-29 SMT)
• 44 NM (82 km) Vs that of a 0.1m2 class target (F/A-18 E/F/G, EF-2000, Rafale B/C/M, Cruise missles)
• 25 NM (46 km) Vs that of a 0.01m2 class target (F/A-18 E/F Block3?, Rafale D?, PAK-FA?, Stealthy cruise missies)
• 14 NM (26 km) Vs that of a 0.001m2 class target (F-35 A/B/C)
• 8 NM (15 km) Vs that of a 0.0001m2 class target (F-22A, B2, F117A)

• 132 NM (245 km) Vs that of a 10m2 class target (F-15, Su-27, SU-31MKI)
• 74 NM (137 km) Vs that of a 1m2 (New USAF Standard) class target (F-16, MIG-29 SMT)
• 42 NM (78 km) Vs that of a 0.1m2 class target (F/A-18 E/F/G, EF-2000, Rafale B/C/M, Cruise missles)
• 24 NM (44.5 km) Vs that of a 0.01m2 class target (F/A-18 E/F Block3?, Rafale D?, PAK-FA?, Stealthy cruise missies)
• 13 NM (24 km) Vs that of a 0.001m2 class target (F-35 A/B/C)
• 7.5 NM (14 km) Vs that of a 0.0001m2 class target (F-22A, B2, F117A)

• 124 NM (230 km) Vs that of a 10m2 class target (F-15, Su-27, SU-31MKI)
• 70 NM (130 km) Vs that of a 1m2 (New USAF Standard) class target (F-16, MIG-29 SMT)
• 39 NM (72 km) Vs that of a 0.1m2 class target (F/A-18 E/F/G, EF-2000, Rafale B/C/M, Cruise missles)
• 22 NM (41 km) Vs that of a 0.01m2 class target (F/A-18 E/F Block3?, Rafale D?, PAK-FA?, Stealthy cruise missies)
• 12.5 NM (23 km) Vs that of a 0.001m2 class target (F-35 A/B/C)
• 7 NM (13 km) Vs that of a 0.0001m2 class target (F-22A, B2, F117A)

• 108 NM (200 km) Vs that of a 10m2 class target (F-15, Su-27, SU-31MKI)
• 61 NM (113 km) Vs that of a 1m2 (New USAF Standard) class target (F-16, MIG-29 SMT)
• 34 NM (63 km) Vs that of a 0.1m2 class target (F/A-18 E/F/G, EF-2000, Rafale B/C/M, Cruise missles)
• 19 NM (35 km) Vs that of a 0.01m2 class target (F/A-18 E/F Block3?, Rafale D?, PAK-FA?, Stealthy cruise missies)
• 11 NM (20 km) Vs that of a 0.001m2 class target (F-35 A/B/C)
• 6 NM （11 km） Vs that of a 0.0001m2 class target (F-22A, B2, F117A)

• 92 NM (170 km) Vs that of a 10m2 class target (F-15, Su-27, SU-31MKI)
• 52 NM (96 km) Vs that of a 1m2 (New USAF Standard) class target (F-16, MIG-29 SMT)
• 29 NM (54 km) Vs that of a 0.1m2 class target (F/A-18 E/F/G, EF-2000, Rafale B/C/M, Cruise missles)
• 16.5 NM (31 km) Vs that of a 0.01m2 class target (F/A-18 E/F Block3?, Rafale D?, PAK-FA?, Stealthy cruise missies)
• 9 NM (17 km) Vs that of a 0.001m2 class target (F-35 A/B/C)
• 5 NM (9 km) Vs that of a 0.0001m2 class target (F-22A, B2, F117A)

• 70 NM (130 km) Vs that of a 10m2 class target (F-15, Su-27, SU-31MKI)
• 39 NM (72 km) Vs that of a 1m2 (New USAF Standard) class target (F-16, MIG-29 SMT)
• 22 NM (41 km) Vs that of a 0.1m2 class target (F/A-18 E/F/G, EF-2000, Rafale B/C/M, Cruise missles)
• 12.5 NM (23 km) Vs that of a 0.01m2 class target (F/A-18 E/F Block3?, Rafale D?, PAK-FA?, Stealthy cruise missies)
• 7 NM (13 km） Vs that of a 0.001m2 class target (F-35 A/B/C)
• 4 NM (7 km） Vs that of a 0.0001m2 class target (F-22A, B2, F117A)

• 119 NM (220 km) Vs that of a 10m2 class target (F-15, Su-27, SU-31MKI)
• 67 NM (124 km) Vs that of a 1m2 (New USAF Standard) class target (F-16, MIG-29 SMT)
• 38 NM (70 km) Vs that of a 0.1m2 class target (F/A-18 E/F/G, EF-2000, Rafale B/C/M, Cruise missles)
• 21 NM (39 km) Vs that of a 0.01m2 class target (F/A-18 E/F Block3?, Rafale D?, PAK-FA?, Stealthy cruise missies)
• 12 NM (22 km) Vs that of a 0.001m2 class target (F-35 A/B/C)
• 7 NM (13 km) Vs that of a 0.0001m2 class target (F-22A, B2, F117A)

Detection Range Formula: [New RCS/Old RCS]^.25 * original detection range = new detection range.

F-22 VS JSF

• The F-22A would be able to detect the JSF at around 35-45km in LPI mode, while the AN/APG-81 on the JSF would be able to detect the F-22A at around 20-25km.

F-15C (AN/APG-63(V2) AESA) Vs SU-30MKI (N0-11M PESA "Bars")

• The F-15C would be able to detect a 10m2 class size target of a SU-31MKI at around 260km, while the SU-31MKI would be able to detect the Eagle at around 245-255km. So basically, it comes down to the better tracking and Air-to-Air missiles. I'd have to give the edge to the Eagle with AMRAAM's.

F-16 Block60 (An/APG-80 AESA) Vs SU-30MKI

• The F-16 Block 60 would be able to detect a 10m2 class target such as the SU-30MKI at around 170-200km, while the SU-31MKI Flanker would be able to detect a 1m2 class target such as the Falcon at around 137km. So, the F-16 would be able to see the Flanker well before it's even detected giving it a much greater chance of maneuvering into postion to get off a shot at higher altitude which would extend standoff range.

F/A-18 E/F Super Hornet (Latest AESA AN/APG-79) Vs SU-30MKI, EF2000, Rafale.

• The maximum detection range of the F/A-18 E/F (AN/APG-79) vs that of a 10m2 class sized target (SU-31MKI) would be 230km, as opposed to the SU-30MKI's maximum detection range of a 0.1m2 class target (F/A-18 E/F) of 78km. Conclusion - The F/A-18 E/F would be able to get off a few AMRAAM's (AIM-120(C7)) before entering the SU-30MKI Flankers engagment window of the R-77.
• The maximum detection range of the F/A-18 E/F (AN/APG-79) vs that of a 0.1m2 class target (Rafale) would be 72km, as opposed to the Rafale's maximum detection range of a 0.1m2 class target (F/A-18) of 55-60km. Conclusion - the F/A-18 would be able to shoot off a few AMRAAM's before the Rafale ever knew it was there.
• (More intresting) - The maximum detection range of the F/A-18 E/F (AN/APG-79) vs that of a 0.05 class sized target (EF-2000) would be 35km, well within the kill enevlope of that of the EF-2000 which would detect a 0.1m2 class target (F/A-18 E/F) at around 60-70km. Conclusion - Doesn't stand a chance without AWACS support.