Business & GA, Commercial, Military

Product Focus: Antennas

By By Barry Rosenberg | June 1, 2010
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Just a couple of years ago, high-speed broadband connectivity at 35,000 feet was still a dream for most commercial and business operators. Everyone knew it was coming; it was just a matter of when.

Now, a couple years since the introduction of Inmarsat’s SwiftBroadband service, antenna manufacturers are seeing their products introduced on virtually every new aircraft delivery. And they can make a good business case for retrofitting antennas on legacy aircraft.

“What has finally happened is that SwiftBroadband as a service hit the market fairly solidly in 2009,” said Michael Wilkerson, director of strategy and business development for the Satcom business unit of Cobham, which includes antenna manufacturer Comant Industries, based in Fullerton, Calif. “Pent up demand for broadband on aircraft is proving to be true, even though the take-up rates aren’t meeting everybody’s expectations due to the economy.”

Factors limiting the speed at which broadband solutions are able to come to market right now include the installation costs, dealing with regulations and Technical Standard Orders, and the effect the economy has had on discretionary expenditures, which means retrofits are in a go-slow mode as modifications are relegated to the back burner.

That doesn’t mean, though, that airlines and other operators aren’t conducting their due diligence now so that they’ll be able to make quick decisions on connectivity and bandwidth when funding is freed up in the near-term future.

“What we’re seeing from the commercial airlines are many requests for retrofit pricing to remove all the classic antennas from their planes and retrofit to SwiftBroadband antennas,” said Norm Pickering, senior marketing manager for Satcom with Esterline CMC Electronics, of Ottawa. “What we’re seeing from the airlines is that they’re working the business case to switch to SwiftBroadband.”

When it does eventually materialize, the retrofit market for broadband antennas will be in the many thousands of units. CMC Electronics alone, for example, has an installed base of about 2,800 classic Inmarsat Swift 64 antennas that will likely all be replaced with SwiftBroadband antennas over the next few years, Pickering said.

“That’s just the portion we’ve sold to. Add in aircraft that have older ball antennas, without even touching on the bizjet market, and you have a very large market from the retrofit side,” Pickering said. “Once the economy keeps improving, I think some of the airlines will jump on this sooner than later, considering that they’re also getting the avionics and satcom antennas for their new aircraft coming out of the factory.”

Making up for a good portion of that still-to-come commercial retrofit business is the military, which, in an airborne environment, is particularly interested in antennas to transmit and receive large data streams from special mission aircraft like C-130J airlifters that are operated by special operations forces, for example.

An inspection of the fuselage of U.S. Air Force Predator unmanned aerial vehicles (UAV) reveals antennas indicative of military requirements, which will only grow as the Pentagon requires intelligence, surveillance and reconnaissance assets to record and transmit in high definition from their onboard cameras.

“You know what’s been happening all the way down to the squad level,” said Wilkerson, referring to the U.S. Department of Defense initiative to bring bandwidth to smaller units, and the challenges of on-the-move satellite communications. “There is no amount of bandwidth that is enough for the amount of information that wants to be moved back and forth.

“In the aircraft world there is really no difference,” he added. “You might have a big surveillance aircraft that’s flying a racetrack on four-hour missions and only making a turn every hour or so. It is still, nonetheless, potentially turning away from the satellite during part of that, and if you’re streaming data the entire time there’s a risk that you could lose lock. So everybody wants to be sure that the antenna configuration they’ve selected will give them performance.”

Intermodulation Issue

The engineering challenges of getting Gigabit Ethernet transmissions on and off an airplane, in the same footprint that is used for older Swift 64 antennas, are varied. Many of them relate to addressing the strict intermodulation requirements of SwiftBroadband versus the looser requirements that have to be met under Swift 64.

“The biggest challenge within industry was the need to meet strict-level intermodulation in the new generation antennas,” said Alan Hnatiw, CMC Electronics product manager for Satcom. “Back in 2005, the industry wasn’t even sure that meeting these new intermodulation requirements could be done in a commercially meaningful way.”

Product managers at other major antenna manufacturers concur that addressing intermodulation in high-bandwidth systems has topped everyone’s engineering checklist.

“Previously, legacy antennas had a certain intermodulation order that you had to hit, which was relatively easy in hindsight,” said Tim Best, product manager for aero antennas and radomes with EMS Aviation, of Ottawa and Moorestown, N.J. “The new SwiftBroadband requirements don’t do as much frequency management so you can get higher orders of intermod, making things that much more difficult. It is a non-linear thing. It was very difficult to go from 19th order to 9th or 7th order. Some people couldn’t make the jump.”

Compounding the challenge of transitioning to SwiftBroadband antennas is that the entire system has to be SwiftBroadband optimized, including not just the antenna but also the diplexer, cabling, transceiver and high-power amplifier.

“More people are coming in looking for systems,” Best said. “The antenna is important, obviously, but it is only one facet of the whole system. As things get more complex, end users like Bombardier are looking for somebody who can give them the expertise to solve the SwiftBroadband conundrum.”

Part of the solution is certainly to combine the functionality of multiple antennas into one. That’s especially needed for application on UAVs, where the amount of real estate on the fuselage is limited, and space for additional antennas constrained.

“Multiple applications in a single antenna is what people want to see,” said Si Robin, CEO of Sensor Systems Inc., of Chatsworth, Calif., who has spent decades in the aero antenna business. “A lot of them come to us and say ‘can you put two or three of these together?’”

That’s the sort of question that Sensor Systems gets from military special operations forces, according to Robin.

“They wanted us to develop one antenna that would cover every frequency from 30 to 512 MHz,” Robin recalled. “Thirty to 512 has never been done before, and especially 30-88 MHz with the gain capability. Normal for antennas is 21 dB (gain). We have come up with a way to do it with an 8 dB. So for every 3 dB it’s twice as good. So you can imagine that the range increased by a significant amount by going from 21 to 8 dB.”

Sensor Systems accomplished that in a nine-inch antenna. The system is installed on C-130J aircraft operated by special forces, Robin said.

Also related to saving fuselage real estate, CMC Electronics chose not to build its SwiftBroadband antenna to the latest ARINC 781 specifications but rather to the older, but still capable ARINC 741 standard from the mid-1990s. That gives the company’s CMA-2102SB (SwiftBroadband) antenna the same footprint as the legacy Swift 64 antenna it is replacing, simplifying the retrofit procedure.

“A lot of people think that SwiftBroadband equals ARINC 781 as far as antennas go. Our 2102 antenna is not a 781 antenna, but it does SwiftBroadband very well,” said Pickering.

“From an interface perspective, the 741 and 781 antennas are similar. But there is a change in the form factor, and we felt it was more important to provide an easier evolutionary path for our customers that didn’t include the structural issues associated with having to rip off one antenna and replace it with another. We have over 2,800 CMA-2102 and CMA-2102LW antennas out in the field. That is a significant retrofit audience that can use the same form factor antenna,” he added.

The enabling antenna technology for Gigabit Ethernet communications to the cabin is either a phased array antenna on top of the fuselage or a mechanically steered antenna on the tail. The phased array antenna has the advantage of being short (2 to 2 1/2 inches tall) and long, making them well suited for air transport fuselages. A mechanically steered antenna has a smaller footprint but is much taller. It also has to be housed in an aerodynamic radome.

“There are enough aircraft out there that operators can take advantage of a tail-mounted antenna to have that simpler and very effective mechanically steered antenna,” said Cobham’s Wilkerson. “It’s when you move into other frequencies like Ku and Ka that you’re almost back to the drawing board.

“We’re seeing the development now of flat-panel antennas for Ku and some Ka, but you still have to steer them in either one or two axes. That means that the device has to have a footprint area that allows it to steer through 360 and whatever elevation angles your design requires. Today that means the antenna is physically large.”

Still, a flat-panel antenna that points is the technology that many of the most capable antenna manufacturers are working on today for introduction some time later this decade. When paired with Ka-band satellite coverage, a network also expected to be more fully built by later this decade, this will undoubtedly lead to high-data-throughput capabilities rivaling those in the most capable office buildings.

Avionics Magazine’s Product Focus is a monthly feature that examines some of the latest trends in different market segments of the avionics industry. It does not represent a comprehensive survey of all companies and products in these markets.


BAE Systems
Ball Aerospace and Technologies
CMC Electronics
DAC International, Inc.
Dallas Avionics
Dayton-Granger Inc.
EMS Technologies
General Dynamics
HR Smith
ITT Industries
KVH Industries
L-3 Communications
Northrop Grumman
NovAtel Inc.
Quantenelektronische Systeme GmbH
Rockwell Collins
Sensor Systems
Starling Advanced Communications
Tecom Industries
Teledyne Controls

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