AEGIS SPY 1- VARIANTES
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ARTIGO COMPLETO:
The US Navy’s Dual Band Radars
The US Navy’s newest light cruiser and aircraft carrier designs offer a wide array of new technologies. One is the Dual-Band Radar (DBR) system, which can be scaled up or down for installation in the new DDG-1000 Zumwalt Class “destroyers”, and the CVN-21 Gerald R. Ford Class aircraft carriers.
The DBR concept involves a significant change from current naval design approaches, and that change is not without risk. The USA’s GAO audit office has identified it as a significant risk to on-time fielding of the USS Zumwalt [DDG 1000], and any more development or testing snags could widen those impacts to include other ships. The radar is beginning to move from design to production, however, following a successful full-power “lightoff” of both DBR radars in an early April 2009 test.
The latest development involves a significant production contract for one of the DBR’s modules…
DBR: Concept and Comparisons
At present, the radars used for scanning large areas and for focused targeting are completely separate pieces of equipment, that are only integrated by the ship’s combat system. The DBR will break from that approach by combining 2 different radar antennas, with the same back-end radar electronics and software driving both. The ship’s combat system will receive a single stream of data, and the radar itself will be able to mix and match its antennas as the situation requires. At the design tier, this approach allows fewer radar antennas, all flush-mounted with the superstructure for maximum stealth. At the tactical tier, integration at the radar level offers faster response time, faster adaptation to new situations, and better utilization of the ship’s power, electronics, and bandwidth. At the life-cycle maintenance tier, it allows one-step upgrades to the radar suite as a whole.
The tactical difference is easier to understand by comparing the present American state of the art with the DBR approach. The US Navy’s DDG-51 Arleigh Burke Class AEGIS destroyers and CG-47 Ticonderoga Class cruisers currently form the high end of its naval air defense capabilities. They use 2-4 different radars in their work, which are combined into a common picture by the ships’ AEGIS combat system.
The rotating AN/SPS-49 radar on the cruisers’ mast offers 2D (range and heading only) very long-range scans in the L-band. It serves as the primary air search radar aboard a wide array of ship types, from aircraft carriers to frigates, and is also used by CG-47 Ticonderoga Class cruisers.
AEGIS ships have a more effective radar at their disposal, however: the AN/SPY-1B/D/E passive phased array S-band radar can be seen as the hexagonal plates mounted on the ship’s superstructure. SPY-1 has a slightly shorter horizon than the SPS-49, and can be susceptible to land and wave clutter, but is used to search and track over large areas. It can search for and track over 200 targets, providing mid-course guidance that can bring air defense missiles closer to their targets. Some versions can even provide ballistic missile defense tracking, after appropriate modifications to their back-end electronics and radar software.
The 3rd component is the AN/SPG-62 X-band radar “illuminators,” which designate targets for final intercept by air defense missiles; DDG-51 destroyers have 3, and CG-47 cruisers have 4. During saturation attacks, the AEGIS combat system must time-share the illuminators, engaging them only for final intercept and then switching to another target.
In an era of supersonic anti-ship missiles that use final-stage maneuvering to confuse defenses, and can be programmed to arrive simultaneously, this approach is not ideal.
The US Navy’s Dual-Band Radar relies on products from 2 different manufacturers, but they’re integrated in a different way. They also use a different base technology. The use of active-array, digital beamforming radar technology will help DBR-equipped ships survive saturation attacks. Their most salient feature is the ability to allocate groups of emitters within their thousands of individual modules to perform specific tasks, in order to track and guide against tens of incoming missiles simultaneously. Active array radars also feature better reliability than mechanically-scanned radars, and recent experiments suggest that they could have uses as very high-power electronic jammers, and/or high-bandwidth secure communications relays.
Many modern European air defense ships, from the British Type 45 destroyers, to the Franco-Italian Horizon destroyers and FREMM frigates, to Dutch/German F124 frigates, use active array search and targeting radars.
Raytheon’s X-band, active-array SPY-3 Multi-Function Radar (MFR) offers superior medium to high altitude performance over other radar bands, and its pencil beams give it an excellent ability to focus in on targets. SPY-3 will be the primary DBR radar used for missile engagements. Many anti-ballistic missile radars are X-band, and the SPY-3 could also be adapted for that role with the same kinds of software/hardware investments and upgrades that some of the fleet’s S-band, passive phased array SPY-1s have received.
On surface combatants, the AN/SPY-3 would also replace the X-band AN/SPQ-9 surface detection and tracking radar that is used to guide naval gunfire, and even track the periscopes of surfacing submarines. On carriers, it would take over functions formerly handled by AN/SPN-41 and AN/SPN-46 PALS air traffic radars, and would work in conjunction with the new GPS-derived Joint Precision Approach Landing System (JPALS).
Lockheed Martin’s Volume Search Radar (VSR) is an S-band active array antenna, rather than the SPY-1’s S-band passive phased array. The Navy was originally going to use the L-band/D-band for the DBR’s second radar, but Lockheed Martin had been doing research on an active array S-band Advanced Radar (SBAR) that could potentially replace SPY-1 radars on existing AEGIS ships. A demonstrator began operating in Moorestown, NJ in 2003. That same year, its performance convinced the Navy to switch to S-band, and to make Lockheed Martin the DBR subcontractor for the volume search radar (VSR) antenna. It also convinced Lockheed Martin to continue work on the project as a complete, integrated radar, now known as “S4R”.
S-band offers superior performance in high-moisture clutter conditions like rain or fog, and is excellent for scanning and tracking within a very large volume. While Lockheed Martin makes the VSR antenna, the dual-band approach means that Raytheon is responsible for the radars’ common back-end electronics and software.
The VSR/S4R’s nearest competitor would be Thales’ SMART-L, an active array L-band/D-band radar that equips a number of European air defense ships, and South Korea’s Dokdo Class LHDs. Unlike the DBR, however, the ships carrying it use the conventional approach of completely separate radar systems, integrated by the ship’s combat system.
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