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SAMPSON Multi-Function Radar



The first prototype SAMPSON Multi-Function Radar was installed on a representative Type 45 foremast at AMS's Cowes site in September 2004.  In 2005 it was moved to the Eskmeals gunnery range in Cumbria.  Source: BAE Systems


The Sampson radar sits atop HMS Daring's mast

The first production SAMPSON Multi-Function Radar prototype, shown on 3 April 2007, just a few days after being lifted on board HMS Daring.  Source: BAE Systems


Background and Development

Western navies are starting to prepare for the revolutionary switch to a new generation of  above water warfare sensors-active phased array multi-function radars (MFRs).

Canada, Germany, the Netherlands, the UK and the US have all firmly embraced active array-based MFR technology.  Naval warfare experts in these countries believe that this type of radar will progressively leave more traditional radar systems obsolete in a military environment of increasing uncertainty and more pressing threats. Theatre threat scenario includes many simultaneous targets that are stealthy, highly manoeuvrable, supersonic and capable of extremely challenging sea-skimming or ballistic flight trajectories and sophisticated electronic countermeasures, in environments that feature adverse propagation phenomena. Requirements call for many simultaneous channels of fire, simultaneous multi-function capability, fast response, an extremely large operational bandwidth, and new electronic counter-countermeasures (ECCM).

Turning Point

According to senior radar engineers in BAE Systems, the "radically different" active array is indeed a major turning point in the field of radar technology: "You're not designing a radar which is fixed in its design, you've got an array that forms a beam and you can do what you like with it. We're moving into software-driven radar, which can deal with different situations and can be easily adapted to deal with future threats.  For instance, should you wish to go to a much higher data rate, for missile tracking or if you want to vector a combat air patrol (CAP) you can do so; this is not possible with conventional radars providing an inherent low data rate.

"It is a proper multi-function system, performing three, four, five or more functions in parallel. The way you sequence the beams wherever you want to in space is truly mind boggling." In fact, industry experts say, "you've got to separate your mind from the go-rounders; you'd almost have to call it a different name. Moving to active array MFRs from conventional radars is the same step as putting jet engines on aircraft".

The current state-of-play in high- performance active array naval MFRs is as follows:
  • the Netherlands, Germany and Canada are developing APAR (Active Phased Array Radar), an I/J-band (X-band) MFR of which seven production systems (for a total of 28 active arrays) have been ordered for the navies of Germany and the Netherlands and are now operational. APAR prime contractor is Thales-Nederland;
  • the UK is developing SAMPSON, an E/F-band (S-band) MFR of which three prototypes and a first-of-class (for a total of eight arrays) have been ordered for the UK Royal Navy. SAMPSON prime contractor is BAE Systems; and
  • the US is developing MFR, an I/J-band system that is destined to equip the service's next-generation class of DD 21 destroyers. MFR prime contractor is Raytheon.


UK MESAR research programme

Looking more closely at the UK program, research in to active array radars goes back over 20 years. In 1982, Plessey (now part of BAE Land and Sea Systems) started a joint development program with Roke Manor Defence research laboratory and the UK's Defence Evaluation & Research Agency (DERA). This led to definition of the MESAR 1 (Multi-function Electronically Scanned Adaptive Radar 1) by 1985 and the subsequent building and testing of this demonstrator by 1989, funded jointly by the company and by the UK Ministry of Defence. MESAR 1 trials ran from 1989-95, and included trials under jamming conditions at DERA's Funtington site near Chichester, as well as trials against live flying targets at the West Freugh instrumented trials range. These flight trials demonstrated multi-function (performing the functions of many radars at the same time) and adaptive beam-forming (virtually immune to jamming) capabilities, while using a partly-populated array with 156 gallium-arsenide (GaAs) semiconductor transmit/ receive (T/R) modules of 2W each. (The radar antenna was designed for 916 modules but the high cost associated with these led to only 156 being installed.) The early T/R-modules used were based on 1980s-generation ceramic thin film technology, one module driving a single radiating element in the array.

Following on to MESAR 1, the same partners embarked on a program to develop and build a second demonstrator, MESAR 2, in August 1995. MESAR 2 is a technology demonstrator that is being used to gather data on the detection of air breathing and ballistic targets in real time. BAE Systems officials say that the MESAR 2 design is largely intended to "confirm and validate performance of MESAR technology in ballistic missile defense" and should be regarded as a "major de-risker for SAMPSON".

MESAR 2 employed an entirely new antenna design although much of the signal processing technology of MESAR 1 was retained. Not only the antenna housing was redesigned but, significantly, a new T/R-module design was introduced. This features microwave solid state power amplification and phase shifting (using 4x4mm GaAs micro-wave monolithic integrated circuit chips) incorporated on 20cm-long T/R-modules. To address issues like cost of ownership, the new equipment is based on low-cost standard printed circuit techniques. In addition, each T/R-module is now designed to carry four transmit/receive channels, for which four separate radiating elements are integrated per module. As such, the MESAR 2 modules can be plugged into the array as line-replacable units (LRUs), doing away with the need for a cumbersome connection with an antenna-mounted radiating element. Being mounted at the face of the antenna, the new T/R-module design vastly reduces the energy losses which limit the performance of conventional systems, BAE Systems claims.

The MESAR 2 demonstrator featured a fully-filled array of 1,264 elements, of 10W radiated power each, quad-packed on a total of 316 T/R-modules. At the beginning of 2000, BAE Systems announced that it had transferred ownership of MESAR 2 to the UK MoD, following contractual acceptance achieved after flight trials in November 1999. This has prepared the way for further trials, including ballistic missile defense, in Scotland and New Mexico. MESAR 2 was located on the DERA ranges at Benbecula in the Hebrides, where it has been subjected to a variety of studies during recent months. Initial trials were undertaken against simulated ballistic missile threats, massed aircraft and chaff. These were followed by static trials against false targets within demanding jamming environments. The process will conclude with performance assessments against multiple threats and sea-skimming missiles in severe clutter.

By 2000 siscussions are ongoing about a potential MESAR 3 demonstrator program, BAE Systems said. "It is the intention on our side and on DERA's side to keep the program going. MESAR 3 would be looking atfurther applications of the technology. It would still be an E/F-band radar, using an active array, but it is not likely to be contracted until more of the MESAR 2 trials have been done; we're talking at least 16 months from now."

MESAR 3 would "obviously go further into BMD applications research" but also include other technologies, such as more advanced signal processing and a new Intelligent Radar Manager (IRM). The last is being developed under a four-year Euro-finder program by BAE Systems in conjunction with Thomson-CSF and the Univer-sity of Madrid. According to BAE Systems, the IRM will involve "advanced artificial intelligence techniques for managing the resources of the radar,"and this would be "typical of the sort of technologies that DERA would want to develop under a MESAR 3 program". Because of this pedigree and the fact that development has been undertaken in conjunction with the UK MoD, DERA and the US DoD, the MESAR program represents the "world's most mature repository of proven active phased array technology," BAE Systems claims. The principles created within the MESAR 2 program are the basis of the SAMPSON multi-function air-defense radar to be fitted to the Royal Navy's Type 45 destroyers (primed by BAE Systems) and are to be incorporated in the company's new land-based ballistic missile defense radar EWACS.

As far as SAMPSON is concerned, this will involve a reduced component count but nevertheless will be very much based on the basic MESAR 2 architecture, according to BAE Systems. Its antenna architecture features a great deal of design work by Roke Manor research laboratory, while the T/R-modules have been designed by Roke Manor and BAE Systems and are to be mass produced by BAE's production plant at Ilford, London.

Array technology
Compared to the 1,264 T/R-elements that populate the MESAR 2 array, SAMPSON will feature two arrays, mounted back-to-back on a rotating (up to 60rpm) antenna structure, with a total of 5,200 elements. In fact, the radar has approximately 650 T/R modules of four channels each, per face of the antenna, equalling 2,600 elements per face.

BAE Systems has also studied multi-face versions of SAMPSON with three, four and even five arrays, including a zenith array looking straight up. More realistically, a half-size version of SAMPSON (for use on smaller warships such as corvettes) is being promoted for export under the designation SPECTAR, and this will comprise a single active array, identical in size, shape and number-of-moduleso the array of which SAMPSON will have two. The company says that the single-face SPECTAR configuration would require less below-decks equipment and lower power, being a cost-effective option for medium-range systems. Getting SAMPSON up and running, however, is the first priority and company officials told IDR that if a customer for SPECTAR were to sign on today, a 36-month delivery time would have to be expected for the first system.

Rotating arrays
BAE Systems says that employing two rotating active arrays, as opposed to four fixed arrays, is "better" because of the high cost involved in procuring the arrays and the problems associated of mounting the relatively heavy arrays as high as possible on the ship, to make maximum use of the available type of ship-defense missile. "You'd want to place the MFR as high as possible in the ship, against sea-skimming missile attacks; getting that extra bit of radar horizon could make the difference in getting that extra salvo away to deal with the leakers," a BAE Systems manager said. Furthermore, the company predicts that enemy tactics for attacking a fixed array-equipped ship will be to concentrate a massed missile raid on one side of the ship, thereby saturating one array while effectively making the other three useless.

The Sampson radar dome, a spherical form has now been adopted.

However, it should be pointed out BAE Systems has in practice primarily adopted a rotating array as a compromise solution driven by cost, and that the weight argument in favour is offset by the added structural weight of rotation-proof housing and, of course, drive motors.  If phased arrays had zero cost, a multi-face fixed set-up would surely have been preferred be preferred as the advantages of a fixed set-up are so significant.  The comment about saturation attacks against fixed arrays have more to do with the missiles that are guided than with the radar being fixed or not.

The two arrays in Sampson are processed separately, and indeed it would be possible to operate Sampson as a single-face radar (in effect creating a SPECTAR). The E/F-band has been chosen as the "best compromise between surveillance and tracking requirements".  BAE Systems has selected Mercury Computer Systems of Chelmsford, Massachusetts, to provide the commercial-off-the-shelf (COTS) equipment that will host the company's core radar processing system, so that it can be used across its entire family of products, including SAMPSON.

Sampson is designed to be interoperable with a range of weapon systems. Within PAAMS, it will work in association with the Aster active radar guided missile family, for which it will provide target designation and E/F-band mid-course guidance uplink. Within the BAE Systems-proposed SIWS (Sampson Integrated Weapon System), the radar system would work with the US family of semi-active radar guided missiles (notably Standard Missile SM-2 Block IIIA and Evolved Sea Sparrow Missile, ESSM). In SIWS, the required I/J-band interrupted continuous wave illumination (ICWI) of targets, as well as missile uplink, would be provided by typically two separate CEA-Mount active array tracking radars developed joint by BAE Systems and Australian company CEA Technologies. SIWS was being offered for the now cancelled Royal Australian Navy ANZAC-class war fighting improvement program (WIP) and is now being promoted primarily in South Korea (KDX-3 program) and Turkey (TF-2000 program).

BAE Systems say that Sampson should be regarded as a long-range sensor, its software-programmable search range (depending on which surveillance domain and update rate is selected) extending out to "several 100s of kilometres" and being described by the company as "significantly more than the 150km-range of APAR" - a performance that is directly related also to the chosen frequency band (E/F-band for SAMPSON as opposed to I/J-band for APAR). 


Claims by BAE Systems

Sampson is claimed by BAE Systems to be "vastly more powerful" than existing systems, it will be able to handle multiple threats simultaneously and is said to be "immune" to jamming. The ability of the computer-based management system to shape and point the radar beam instantaneously in any direction, coupled with its ability to change or adapt the radar characteristics in real time in response to current and future threats in an environment of heavy jamming and land and sea clutter, enables SAMPSON to perform a number of tasks simultaneously.  As an example, the radar may employ a wide variety of different waveforms, each optimized for certain search angles and/or environmental conditions (for instance using moving target indication waveforms in the lower regions of the search volume).

BAE Systems claims enhanced weapon system effectiveness thanks to Sampson, including the following capabilities:

  • long-range detection of stealthy targets with a significantly lower false alarm rate, leading to earlier weapon alert (the radar can initiate tracks within the "first look" because of its 60: look-back capability within the 120: field-of-view that the rotating array covers);
  • rapid track formation, leading to an earlier fire-control solution;
  • accurate tracking (with full hemispherical coverage up to the zenith position, 90: elevation directly overhead), leading to an improved fire-control solution;
  • target classification, leading to imp-roved weapon allocation (Sampson's ability to manage its radar energy would allow such identification features as raid discrimination, target size estimation and non-cooperative target recognition);
  • multiple engaged tracks, allowing more channels of fire (SAMPSON would be capable of engaging "several tens" of tracked targets simultaneously, while with a conventional tracking radar the maximum number would be three);
  • active jammer cancellation, allowing operation in intense electronic countermeasures (a large part of the MESAR program was devoted to developing these techniques); and
  • high availability, providing extensive redundant channels and reliable components, both in the T/R-modules and in the processing.

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 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 in to PAAMS is "more of a historic nature, associated with [the] work sharing issues" that were a huge problem during the trilateral Project Horizon

This claim is rather an over simplification.  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 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).


SAMPSON Contract
BAE Systems Insyte is under contract to supply Sampson radars to the UK-variant of the Principal Anti-Air Missile System (PAAM(S)) prime conractor  to UKAMS - a 100% owned subsidiary of MBDA

The first production Sampson radar being lifted aboard HMS Daring on 30 March 2007

The original full scale engineering contract, worth well in excess of £100 million (then US$154m), was awarded in October 2000 and required the delivery by 2004 of three pre-production-standard prototype radars for test and reference purposes, plus the first of the up to 12 radars required for the overall Type 45 program.  It was then expected that series production of 11 additional SAMPSON systems, to take place on a new assembly line in the so-called 909-Building at BAE Systems' Cowes facility on the Isle of Wight, would kick off around 2003.

A follow on contract for five more production Sampson's for Type 45 destroyers was awarded in December 2003.  In August 2005 development and production engineering problems led to a rescheduling of deliveries - a delay which is believed to a major cause of the delay in expected in-service date of the first Type 45 destroyer from November 2007 to December 2009.

In 2004 and 2006 the first two prototype radars were located at the Eskmeals gunnery range in Cumbria and on the Longbow Sea Trials Platform being commissioned in Portsmouth Naval Dockyard. In late 2006 the final prototype was installed at the Type 45 Maritime Integration & Support Centre (MISC) at Portsdown Hill, Portsmouth.

The milestone is significant to the SAMPSON programme marking the delivery of the third and final prototype system.

Physical installation of the first production radar on HMS Daring finally began on 30 March 2007.



 © 2004-7 Richard Beedall unless otherwise indicated.