A makeover for top-heavy Navy ships?

• Author: Jean, Grace V.
• Position: INSIDE SCIENCE + TECHNOLOGY

* If one looks at photos of modern day warships and compares them to conceptual drawings of future Navy vessels, the most striking difference is the lack of antennas on the advanced gray hulls.

It's not that future ships won't need communications, radars and electronic warfare systems. But there will be fewer masts and, as a result, noticeably less antennas and arrays poking out the tops of the deckhouses. And if the work of Office of Naval Research scientists comes to fruition, those "forests" of antennas might one day disappear altogether as radio frequency apertures are integrated into the hulls and superstructures of the ships themselves.

"We're really trying to bring about a new way of designing Navy topsides," says Betsy DeLong, deputy for transition and innovative naval prototypes in the office's command and control technologies department.

As the demand for electronic technologies aboard combat vessels grows, the sheer number of antennas that have popped up on warships has doubled in the last decade. Surface combatants that once carried only 40 to 75 antennas are now sailing with as many as 150.

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That's generating a slew of problems for sailors. Ships have limited real estate available for antennas, especially at their pinnacles. Increasing numbers of antennas mean engineers have to squeeze them in at closer proximity to other arrays.

"When you have lots of different apertures all around your topsides, you have issues of blockage, and you have issues of these antennas interfering with each other," says DeLong. Such electromagnetic interference can have detrimental effects on the functionality of combat systems below decks, particularly when multiple networks are in use. Optimizing those technologies in the saturated airwaves environment also is a challenge for engineers.

Moreover, the antennas tack on weight and throw off the ships' center of gravity. "Whatever weight you add to the mast, you have to add to the keel for stability," says Steven Russell of ONR's ships and engineering systems division.

Such increases could translate into expanding the size of hulls, which raises costs tremendously at a time when shipbuilding budgets are being squeezed.

Scientists believe that they can help reduce those costs by miniaturizing many of the antennas' electronic components--the phase shifters, the high-powered or low-noise amplifiers and others--and by integrating them into more efficient, wideband arrays that will...