January 2019 • Vol 52

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Jane’s InternationalDefence Review

Patriot

P atriot is one of the most widely fielded and well-known Western air-defence systems, having served

its user base for 34 years in a series of continuously updated versions. A ‘system of systems’, Patriot comprises several distinct vehicles and major mission system assem-blies that are interconnected.

A Patriot battery in the latest Configura-tion 3+ standard includes several core compo-nent systems, each mounted on one or more trucks and trailers – the AN/MPQ-65 Radar Set (RS), M903 Launch Stations (LS), AN/MSQ-104 Engagement Control Station (ECS), and several supporting systems for power generation and communications, including the AN/MRC-137 Communications Relay Group, OE-349/MRC Antenna Mast Group,

and AN/MSQ-24 Electric Power Plant (EPP III). These enable the firing of the system’s interceptors: the MIM-104 series missile that includes the MIM-104E Patriot Advanced Capability 2 (PAC-2) Guidance Enhanced Missile – Tactical ballistic missile (GEM-T), MIM-104F PAC-3 Cost Reduction Initiative (CRI), and MIM-104F PAC-3 Missile Segment Enhancement (MSE).

The RS is the name given for the complete radar vehicle, comprising the Raytheon AN/MPQ-53 or AN/MPQ-65 radar and associated systems mounted in a shelter, that are in turn mounted on an M-860 trailer and towed by a M983 tractor truck. Unlike many larger air-defence systems, Patriot utilises a single radar for search, acquisition, and targeting.

The radar is also used for flyout guidance

with missiles directed via the track-via-mis-sile (TVM) principle. Rather than comput-ing course corrections in the missile, using the TVM process the missile transmits this information via two flush-mounted antennas on its tail to the ECS ground station, which computes and sends course corrections back to the missile.

TVM is a hybrid of traditional semi-active radar homing and command guidance. The main advantage of the TVM approach is that the target is less likely to know it is being engaged because although it is aware it is

Patriot games: Raytheon’s air-defence system continues to proliferateWith Poland, Sweden, and Romania signing contracts in 2018, the Patriot user community has grown to 16 countries, making it one of the most widely operated systems of its type. Despite entering service over 30 years ago, the system is still being actively developed and equipped to address future threats. Jon Hawkes reports

Patriot LS mounting two PAC-2 missile canisters. The LS is connected to the AN/MPQ-65 radar and AN/MSQ-104 ECS for firing. IHS Markit/Patrick Allen: 1703824

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being illuminated by a ground radar, it is not being illuminated by a missile and so cannot readily discern whether it is being tracked or is being engaged. As Patriot utilises a single radar for search, acquisition, targeting, and guidance, it can be difficult for a target to discern what stage in this process it is being illuminated for, increasing the reaction time and therefore the system’s chance of a hit.

The AN/MSQ-104 ECS is the battery-level command-and-control (C2) node, and the only manned element of the system during operation. Manned by two operators, the ECS collates information from the RS and enables the users to initiate the launch of interceptors from system-recommended launchers within the battery. Patriot is extensively automated and seeks to provide the operator with a best solution for approval or rejection, rather than leave users to discern the information them-selves. Once initiated, a target would be intercepted by the MIM-104 series missile, which has been developed into more than 14 production versions.

System developmentsPatriot first entered service in 1984, but the Patriot of 2018 is radically different. “There is no legacy Patriot,” said Bob Kelley, a senior man-ager at Raytheon Integrated Defense Systems. “Virtually everything, short of a few heating and cooling fans, has been replaced since 2011.”

Recent activity has largely focused on incremental hardware and software upgrades meant to maintain relevance and capability against evolving threats. Software updates are batched under Post Deployment Build (PDB) releases, with the most recent, PDB-8, having been fielded since early 2017 by the US Army for a December 2017 initial operating capability (IOC) and deployment to the global Patriot user base from 2019.

PDB-8 leverages the new Patriot Modern Man Station (MMS), Radar Digital Processor (RDP), and Modern Adjunct Processor (MAP) for increased system reliability; has an enhanced identification, friend-or-foe capability; provides better radar search, target detection, identifica-tion, and classification capability; and utilises a redesigned fire-solution computer with more than 50% additional processing power. The software is also compatible with the army’s new Integrated Battle Command System (IBCS), a C2 station provided by Northrop Grumman to enable the integrated operation of a range of sensors and effectors within a battlespace.The RDP kit centres around a ruggedised

commercial off-the-shelf (COTS) solid-state digital processor that provides a 10-fold increase in reliability over the precursor analog compo-nents, resulting in an overall 40% improvement in reliability for the radar system. The RDP kit cuts battery level replaceable component units from 759 to 56, reducing the spares and mainte-nance burden and costs over a system’s life cycle.

Modern COTS components have been utilised throughout the system – with all processors, including the MAP, being COTS items – upgrad-ing the system’s processing capabilities and providing for a range of future enhancements and improvements, including the MMS and its associated software.

AESA GaN radarTo go beyond incremental improvements, Ray-theon has developed a new active electronically

scanned array (AESA) gallium-nitride (GaN) 360° radar. Poland (under the Wisla pro-gramme) has expressed a desire to procure such an AESA GaN 360° radar for its Patriot systems, with high-level discussions ongoing at the time of writing. In addition, Raytheon is developing a separate entirely clean-sheet designed radar to compete for the US Army’s Lower Tier Air and Missile Defense Sensor (LTAMDS) requirement that seeks a new sensor for the Patriot system, capable of increased range and power with 360° simultaneous detection and tracking.

Two offerings, one by Lockheed Martin (based on its AESA Radar for Engagement and Surveillance) and Raytheon’s AESA GaN were down-selected for technical maturation and risk reduction (TMRR) activity in

The legacy AN/MPQ-53 has been extensively upgraded since its entry into service in 1984, with the latest version, the AN/MPQ-65, having had essentially every component upgraded.

One of Raytheon’s AESA GaN radar prototypes.

Raytheon: 0044350Raytheon: 1740747

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October, but the programme was reopened to wider competition in November, with a so-called ‘sense off’ to decide a winning bidder in 2020.

Originally sought as a complete replace-ment to the Patriot system, the requirement has evolved and now seeks to replace the AN/MSQ-65 radar, recognising the need to field a capability in the short term, and that develop-ments in Patriot’s interceptors have kept the system capable against contemporary threats.

“The US Army has placed stressing require-ments on the programme” said Kelley. “Once we fully understood the requirements we knew an upgrade was not sufficient. What

we are doing is a new bottom-up radar.” The new radar provides 360° simultaneous detec-tion and tracking, with early concept designs mounting a large primary antenna and two smaller quarter panel antennas to provide 360° coverage. Testing has shown the ability to seamlessly transfer target tracking from one array to another.

Lockheed Martin declined to discuss its LTAMDS offering.

AESA is a significant upgrade over the passive scanned array in the existing system, changing the way the Patriot radar searches the airspace from a single amplifier, beam, and receiver, to an array that has individual

amplifiers, phase shifters, and receivers with each element.

The technology is inherently more resist-ant to electronic jamming via rapid frequency hopping, preventing traditional antiphase jam-ming in which a radar’s signal is identified and broadcast back at it out of phase to essentially nullify the signal return. Efforts to circumvent this are also mitigated by AESA, which can utilise concepts such as pulse modulation to randomly distribute frequencies across a wide band within individual pulses.

Aside from significant space and weight savings from the integrated transmitter and receiver process, the technology is faster to scan, and produces a higher resolution scan as the beam is static during acquisition. In addi-tion, multiple beams can be utilised to enable simultaneous continuous tracking rather than interlaced tracking with a small but poten-tially significant latency between each target’s return and overall degradation of the scan picture.

AESA has resilience due to the use of individ-ual components, meaning if one fails the sys-tem continues to operate at a mildly degraded capability, rather than the sole transmitter failing and shutting down the entire system.

Modern Man StationPatriot faces sophisticated and rapidly devel-oping threats. It is a high-profile and widely fielded system, and its potential adversaries understand it relatively well as they evolve to exploit or overwhelm its weaknesses. Continu-ous software upgrades alongside the new radar being procured under LTAMDS are intended to provide a major capability improvement in preventing the hardware from becoming overwhelmed. However, the issue of operator task overloading must now also be resolved by new hardware and software in the Patriot’s fire-control centre, the ECS.

MMS is the name for Raytheon’s over-hauled operator stations within the Patriot ECS, introduced from the PDB-7 system upgrade. The existing operator consoles date back to the system’s introduction in 1984, with large cathode-ray tube displays and outdated switches and light boards. The new stations utilise two vertically mounted colour touchscreen displays with keyboard and mouse input, replacing hundreds of physical switches and indicators with a more intuitive PC-style man-machine interface.

This is designed to increase operator effectiveness, situational awareness, and the speed and accuracy with which users

The D-PICC condenses the Patriot ICC command post into a deployable system that fits in seven flight cases. This replaces a legacy system that was carried by several trucks and tactical utility vehicles and vastly increases the deployability of the system.

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Raytheon’s WMI provides a significant capability enhancement over legacy software, with the original green and black cathode ray tube screen replaced with a 3D colour interface providing increased situational awareness and engagement efficacy.

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can operate the system. In addition, train-ing is more straightforward, with new users not having to learn about the often-obtuse 1980s technology.

Leveraging the new MMS interface is the Warfighter Machine Interface (WMI), a software upgrade that overhauls the dated 2D, black and white interface to a modern 3D ‘video game like’ colour interface. “Young soldiers coming through are familiar and comfortable with video games. It is very dif-ficult to train them on the old display. There is nothing intuitive about that, it is all rote memorisation,” said Kelley.

“WMI is intuitive, when a kid buys a game, they don’t read the manual that comes with it, yet within 90 minutes they are experts. It is an oversimplification but the concept is valid.”

The new interface displays the operating environment in a 3D image that can be rap-idly reconfigured and manipulated to display required information for the operator.

The legacy interface has over 100 tabs, and extensively uses codes and references to denote statuses and threats.

An operator has to have a high level of familiarity and experience to operate the system quickly, and all this combined with the cross referencing and memorisation of sometimes unintuitive concepts.

The WMI displays information on a single, Google Earth-like view. Extensive use of colour and togglable layers enable rapid digestion and analysis of data; tasks such as determining if an aircraft is in a safe passage corridor change from cross referencing at least three tabs for textual data, to a simple at-a-glance view of an icon in a 3D map with overlaid symbols.

As Patriot operators increasingly find themselves working in a large geographic environment, interconnected with more co-operative sensors and platforms, systems such as WMI are important for leveraging the additional information but also for avoiding becoming buried and paralysed by it.

The first WMI-equipped brigade is to be fielded in mid-2020, with the rest of the US Army’s Patriot units converting from 2022. Both MMS and WMI can be applied to any legacy Patriot operator, and conversa-tions were ongoing between Raytheon and multiple international users as of the time of writing.

Dismounted PatriotFor larger formations at the battalion level,

the Patriot system is managed and connected to wider air-defence and sensor networks by the AN/MSQ-ll6 Information Co-ordination Central (ICC): a battalion-level C2 station that directs the battery level ECS station identification and engagement activity. The enduring issue at this level has been one of flexible deployment of Patriot – while a Patriot battalion is notionally four batteries and an ICC HQ (Headquarters) unit, in most recent deployments only two batteries are deployed alongside their HQ, leaving two batteries without a C2 node and unable to contribute to other requirements. Reducing the size and increasing the transportability of the ICC was desired to improve deployabil-ity and enable the fielding of these reduced size patriot formations.

Raytheon started with the existing ICC configuration – which comprises two five-ton trucks; two 30 kW generators; antenna and communications unit; and all associated

logistics, fuel, and equipment – and reduced the physical, manpower, and logistical foot-print. The resulting Dismounted Patriot ICC (D-PICC) comprises seven flight cases that can be packed into a standard quarter-ton tactical utility vehicle or a single pallet on an aircraft. The first five D-PICCs began delivery to US Army units based in Japan in December 2017, completing in February 2018.

MissilesThe MIM-104 series of missiles has been developed into more than 14 production ver-sions. Most in-service Patriot units now uti-lise one, or a combination, of three missiles – the Raytheon MIM-104E PAC-2 GEM-T for engaging aircraft and air-breathing targets such as cruise missiles, and the Raytheon MIM-104F PAC-3 CRI or Lockheed Martin PAC-3 MSE engaging ballistic missiles.

The PAC-2 GEM-T is a conventional inter-ceptor, in that it seeks to defeat the target via the use of its M248 blast/fragmentation warhead. PAC-3 missiles are a completely different design, being smaller in size and defeating targets with a hit-to-kill (HTK) principle, whereby the target is destroyed by the kinetic energy imparted from the physi-cal collision of the interceptor with its target. The missile is equipped with a ‘lethality enhancer’ – a small 408 g fragmentation war-head used to create a fragmentation ‘cloud’ around the missile during interception of air breathing targets.

SkyCeptorTo provide another effector option, Ray-theon and Israel’s Rafael Advanced Defense Systems have developed the SkyCeptor as a lower-cost interceptor.

“Missile defence is a complicated challenge

Concept image of the SkyCeptor missile firing from a Patriot-based ground unit. It is a development of the Rafael/Raytheon Stunner interceptor.

US Army Patriot PAC-2 (left) and PAC-3 (right) LS deployed to Southwest Asia in 2009.

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because it’s cheap and easy to create threats, but difficult and expensive to defend against them,” said Ralph Acaba, vice-president of Raytheon Program Management Excellence.

SkyCeptor could add another capability to the Patriot system by providing a low-cost HTK interceptor to fill the low end of the capability spectrum, where use of a PAC-2 or PAC-3 MSE would be excessive in cost or capability compared with the target.

The missile is based on the Stunner, the interceptor used in the Israeli David’s Sling system, also jointly developed by Raytheon and Rafael. Development of the Stunner began in 2007; it is a two-stage missile utilising a ground-based Elta ELM-2084 mobile S-Band 3D AESA multimission radar for targeting and guidance, with a primary target set of large-calibre long-range rockets and short-range ballistic missiles.

The Stunner is in full-rate production and was first operationally fired in July 2018, where two Stunner interceptors engaged long-range rockets fired at Israel. Further upgrades to Stunner’s software and algo-rithms are planned under three block upgrade programmes, which are to be leveraged for SkyCeptor’s development.

Poland has expressed a desire to acquire the SkyCeptor with its Patriots, with an offer of up to 60% of the missile being produced in Poland, and transfer of technology enabling Poland to pursue export and further domestic opportunities with the missile in the future. A potential avenue would be for Poland to acquire reduced numbers of PAC-2 and PAC-3 MSE missiles in favour of primarily operating the SkyCeptor as the Patriot’s interceptor, therefore reducing cost of acquisition and operation. However, announced plans for Wisla Phase I to date only refer to a PAC-3 MSE acquisition.

PAC-2 GEM-T GaNWhile the PAC-3 interceptors provide protec-tion against ballistic missile threats, the ‘legacy’ capability to defeat air-breathing targets, including fixed-wing and rotary-wing aircraft and cruise missiles, remains primarily the role of the PAC-2 GEM-T missile, manufac-tured by Raytheon.

Where PAC-3 utilises the HTK principle, the PAC-2 retains the traditional blast/frag-mentation warhead, so the PAC-2 can miss by a little and yet still achieve a kill on the target, breaking the airframe apart or critically dam-aging it with fragmentation.

Although it entered service in 2015, the

GEM-T version of the MIM-104 missile contin-ues to be developed with Raytheon injecting its GaN technology into the missile. “We are developing a GaN solid-state transmitter for the GEM-T,” said Kelley, “this will replace the existing travelling wave tube design and has a range of benefits”.

These include obviating the need to replace a range of parts during missile recertifica-tion over its life cycle, and increased reli-ability. Readiness and responsiveness is also increased, with the time required to warm and ready a missile for firing reduced from minutes to seconds.

PAC-3 MSEThe most recent version of Patriot’s missile interceptor is the Lockheed Martin-designed and manufactured MIM-104F PAC-3 Mis-sile Segment Enhancement, that was first

fielded in 2015 with a primary focus on ballistic missile defence (BMD). Larger than the precursor baseline PAC-3, the MSE has increased altitude and range, as well as larger flight control surfaces and structural modifications to accommodate the larger and heavier airframe. The longer range is obtained by a larger 11.4-inch (28.95 cm) diameter two-stage motor, replacing the 10-inch single-stage motor in the PAC-3. The larger missile results in a reduced launch capacity, resulting in a reduction from 16 PAC-3 missiles to 12 PAC-3 MSE missiles per LS, although the capability to mount a mixed load, typically one or more of PAC-2 GEM-T, PAC-3, and PAC-3 MSE is retained.

As the latest and most capable fielded interceptor, MSE is being actively sought by most global Patriot users, with sales agreed or approved pending final negotia-tion with South Korea (64 missiles), Poland (208), Romania (168), and Sweden (200) in 2018. On 2 November the US government approved the PAC-3 MSE release to Germany for integration with its future MEADS-based TLVS air and missile defence system. Recognising the demand for the missile, Lockheed Martin announced in July that it intends to ramp up production to build a stock of missiles to enable the company to rapidly respond to customer demand. Doing so will require a production rate of about 500 missiles per year, necessitating a new production line. With PAC-3 no longer manufactured, MSE remains the only high-end HTK-based BMD interceptor in produc-tion for Patriot. 

First published online: 16/11/2018v

CommentThe US Army’s LTAMDS requirement is, like many US programmes, something of a benchmark, with the selected solution in effect becoming the de facto solution for all global Patriot users seeking to similarly upgrade radar capabilities.

Some confusion has arisen following the selection of Lockheed Martin and Raytheon for TMRR, followed less than a month later by the reopening of the programme for broader participation. This will enable the other two teams that were not selected for TMRR – Northrop Grumman and Technovative Applications – to compete for the requirement again.

The so called ‘sense-off’ in which competitor offer-ings will be assessed is scheduled for May to June 2019,

with each company given two weeks to demonstrate its system’s capabilities against tactical ballistic missile live targets, digital radio frequency memory jammers, pole jammers, and PAC-3 MSE Radio Support Unit test sets. The systems will be required to demonstrate full performance with the rest of the Patriot system, as well as broader interoperability with the army’s Northrop Grumman-designed IBCS Engagement Operations Center.

The winning company is to be awarded a contract to produce six LTAMDS for qualification and trials ahead of an IOC in the fourth quarter of fiscal year 2022, after which additional contracts are expected to roll the new radar out across the Patriot fleet.

The Lockheed Martin MIM-104F PAC-3 missile firing from an M903 LS.

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