Background and DevelopmentWestern 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).
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:
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.
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:
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).
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.