Warship radar technology designers set sights on next-generation Navy cruiser

May 14, 2009
 Program focus -- The Lockheed Martin Corp. Maritime Systems & Sensors (MS2) segment in Moorestown, N.J., and Raytheon Integrated Defense Systems in Tewksbury, Mass., are preparing for the expected release of the U.S. Navy's radar systems requirements for the next-generation cruiser surface warship, now called CG(X).

By Edward J. Walsh

The Lockheed Martin Corp. Maritime Systems & Sensors (MS2) segment in Moorestown, N.J., and Raytheon Integrated Defense Systems in Tewksbury, Mass., are preparing for the expected release of the U.S. Navy's ship radar systems requirements for the next-generation Navy cruiser surface warship, now called CG(X).

Both companies are stressing compliance with Navy "open-architecture" mandates, radar technology risk reduction, and the need to meet new airborne and missile threats for next-generation radar systems.

The Navy has said that the CG(X) plan and its military radar development will be announced this year, aiming at construction of a new cruiser class focused on fleet air defense and ballistic missile defense (BMD), to replace the Ticonderoga (CG 47) class of Aegis guided missile cruisers. The 2010 defense budget request from the Obama Administration would delay the new cruiser program.

New cruiser plan

In 2007 Navy officials said they needed 19 of the new class, but budget constraints and new thinking about the size of the fleet may reduce the number. In April, Under Secretary of the Navy nominee Robert Work said he supported delaying the start of the CG(X) program for four years and instead build more than the 55 Littoral Combat Ships now planned.

Lockheed Martin is the Navy's longtime supplier for the SPY-1(v) Aegis area-defense radar aboard the Ticonderogas and Arleigh Burke-class (DDG 51) destroyers. Raytheon builds the combat system for the Navy's amphibs and carriers and is systems integration lead for the new three-ship class of Zumwalt (DDG-1000) destroyers.

The companies now are collaborating on testing of the dual-band radar (DBR), the primary air-defense radar for the DDG-1000 and the Gerald R. Ford-class (CNV 78) aircraft carriers, three of which are planned. Raytheon builds the SPY-3 multi-function radar (MFR) segment of the DBR and MS2 provides the volume-search radar (VSR). A production contract is expected this year.

Jim Barry, technical director for Seapower Capability Systems for Raytheon IDS, says that the S-band VSR operates at a frequency of about 3 gigahertz for wide-area search and tracking of high-altitude targets, including manned aircraft. The X-band SPY-3 MFR, with a smaller aperture than the VSR, carries out precision detection and tracking of surface targets, such as small craft and submarine periscopes. The SPY-3 higher frequency, about 10 gigahertz, is able to overcome the distortion caused by atmospheric clutter above the sea surface.

Analysis and alternatives

The CG(X) has gone through an extensive analysis of alternatives that considered all aspects of ship design, including potential use of a nuclear-powered propulsion plant. Navy officials say that the radar requirement "now is the driver" for continuing CG(X) analysis.

The Navy says that the CG(X) radar must be effective against aircraft, anti-ship missiles, and ballistic missiles in the boost, mid-course, and terminal phases. The requirement will dictate size and sensitivity of the radar array, and power requirements. The size and weight of the radar also affects deckhouse and hull design.

Stan Orza, director of Navy radar programs at Lockheed Martin MS2, says that the company has invested heavily in solid-state phased-array radars, leading to development of the S-band VSR component of the DBR. The DDG-1000, he says, will be the first Navy ship to be fitted with an active S-band solid-state radar.

He says that "We've been embracing open architecture to provide a 'leap-ahead' capability for current and future threats—the OA approach is across the whole radar, for both hardware and software, for digital RF and microwave."

These technologies support development of digital-array radar, based on digital beam-forming techniques capability already built into the VSR antenna. Orza says MS2 is using the same technology as a key enabler for the Army's EQ-36 counter-battery radar.

Radar evolution

The MS2 effort, he adds, started about 1999 with the Navy's S-band Advanced Radar (SBAR) program, funded initially through the Missile Defense Agency. The company's enhancements for Navy radars started with the SPY-1A, the baseline "blue-water" radar for the Ticonderogas and continued with the SPY-1B and SPY-1D(v), which extended the SPY capability to detection of low cross-section targets through intense surface clutter.

The company currently is focused on improving radar capability to provide real-time discrimination for BDM, achieved through use of a multi-mission signal processor, an OA-compliant commercial off-the-shelf (COTS) product provided by Mercury Computer. The processor also is incorporated into the Aegis architecture being upgraded in an comprehensive Aegis modernization for the Burkes and newer Ticos. Currently three cruisers: Shiloh, Lake Erie, and Port Royal are BMD-capable.

MS2, Orza adds, is participating in a collaborative effort with the U.K. Royal Navy called ARTIS (advanced radar integrated system testbed) that has demonstrated digital beam-forming technology and a second effort with Japan to modify its Aegis-equipped Kongo-class destroyers for BMD capability.

Solid state radar

The centerpiece of the company's Navy radar work, Orza says, is scalable solid-state S-band radar (S4R) initiative, which is evolving in three generations of radars. The first generation, now in production for the Army's EQ-36, incorporates S-band and OA-compliant commercial technology and led to the Navy's decision to use S-band technology for the DDG-1000 VSR. The first-generation S4R also is incorporated in the now-completed VSR engineering development phase. The VSR now is being tested at the Surface Combat Systems Center at Wallops Island, Va., along with Raytheon's SPY-3 MFR.

For the second generation S4R effort, the company built a radar demonstrator, a scaled version of the VSR with an eight-foot aperture to evaluate technologies to be integrated with the VSR production system. The demonstrator has tested various approaches to OA compliance for design of the transmit-receive module design by use of multiple technologies, including two generations of silicon carbide, high-power amplifiers, and high-voltage gallium arsenide.

Orza adds that while the DDG-1000 VSR was designed for conventional analog beamforming, the second-generation S4R introduces digital beamforming, aimed at the BMD mission.

The company's solid-state family of radars, he says, provides three configurations for three missions: a scaled-down littoral combat radar (LCR) for ship-self defense in littoral environments, probably using a five-foot aperture; an air-defense radar (ADR) for the traditional Aegis area air-defense mission using an eight-foot aperture; and a multi-mission defense radar (MDR) to meet the BMD requirement with an aperture as large as 12 feet.

High levels of integration

For the CG(X), Orza says, MS2 is looking at a third generation of S4R technology for an advanced MDR, and is investigating advanced packaging and higher levels of integration in semiconductor components.

Raytheon's Barry says that the company's "initial increment" for the CG(X) radar will be a system much like the DBR going aboard DDG-1000 and the CVN-78, with BMD added for the VSR component. A key DBR attribute, he adds, is that both the VSR and the SPY-3 are controlled by a single COTS data processor provided by IBM that can "interleave" the emissions of the two systems to defeat jamming of one or the other.

A critical challenge, he adds, is "right-sizing" radars, or finding the optimum point in a radar's capability spectrum that can be applied to the threat.

"Radar is going to drive the size of the platform," he says. "Because the BMD mission is executed outside the atmosphere, it's necessary to determine how large a radar the ship can accommodate, and when it's necessary to use multiple sensors netted across the globe, whether ground-based, space-based, or maritime sensors."

Raytheon is exploring the use of its COTS-based Tactical Component Network (TCN) developed by the company's Solypsis business unit. The TCN was proposed several years ago as a possible alternative to the Navy's Cooperative Engagement Capability (CEC), which also is built by Raytheon IDS, and now is in service aboard Ticos, Burkes, and Wasp- and San Antonio-class amphibs.

The TCN, Barry says, could serve as a global network force multiplier that provides an "engage on net" capability, enabling ships to engage targets by taking track data via the network, and thereby avoiding the need to build very large ships to support very large radars. Such a network extends the capability across the battlespace, he says.

Editor's note: Edward J. Walsh is with the U.S. Office of Naval Research in Arlington, Va.

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