For keeping in touch, satcom antennas provide a vital link

 - October 8, 2007, 5:30 AM

Nobody knows for sure who first coined the term “office in the sky,” but whoever it was, he or she must feel a certain level of vindication that this over-promise of a marketing slogan has at last blossomed into something approaching reality. Today, passengers flying aboard the most copiously outfitted business jets have Internet and local-area network connections, state-of-the-art telephones, satellite links, television monitors and fax and copy machines. They are never more than a few mouse clicks from e-mail and corporate networks, meaning that the time it takes to travel between meeting places can be just as productive as the hours spent in the boardroom or office.

Communicating with the world beyond the airplane’s pressure vessel is no easy feat, and there is no more important piece of equipment for accomplishing this task than the satcom antenna. This highly sophisticated bridge between the passenger compartment and the world below gives passengers access to a network of Inmarsat satellites capable of handling voice transmission and data feeds. As this satcom service expands to include lower-cost voice options and higher-speed data services, manufacturers will be tasked with bringing to market smaller and lighter antennas designed to fit on the widest number of aircraft types possible.

One such manufacturer is EMS Technologies of Ottawa, Ontario, Canada. The company recently introduced the new AMT-3800 satcom antenna, a fuselage-mounted, phased-array that can provide Inmarsat Swift64 data service in midsize and super-midsize business jets. EMS Technologies’ best-selling antenna, the AMT-50 dish, is too big to fit on anything but the largest business jets, and operators had been asking for a low-profile phased-array antenna that could be mounted on the top of the fuselage.

The $100,000 (list price) AMT-3800 measures 1.8 inches high, 12 inches wide and 36 inches long and is compatible with all of the company’s Swift64-based hardware. It is an Inmarsat Aero-H/H+ high-gain antenna that its maker says is suitable for mounting on the fuselages of just about all sizes of corporate aircraft. Specifically targeted for use on smaller midsize jets and helicopters, the antenna has been gaining attention since it became available late last year, according to the company.

“Combined with the HSD-128 Swift64 satcom terminals we offer, the AMT-3800 makes it possible for operators of smaller business aircraft to have the new Inmarsat high-speed data services,” said Neil MacKay, senior vice president and general manager of the EMS Satcom division. “There is no question that for aircraft large enough to fit tail-mount antennas, that is still the optimum position for both satcom and direct-broadcast TV. But with the AMT-3800, EMS brings to midsize, and smaller, aircraft the levels of performance and reliability that have made the AMT-50 a best seller.”

Satcom equipment manufacturers are turning to the lower echelon of business aviation to meet a growing demand for voice satcom and particularly high-speed data services in airplanes that before now could not be fitted with such gear due to the size of antennas. As components continue to shrink and operators begin buying and installing satcom equipment for their midsize jets, the industry could experience a new wave of competition to meet the demand.

Chelton Chimes In

There are already signs that the market is heating up. Lewisville, Texas-based Chelton recently introduced two new Swift64 data satcom systems, along with side- and tail-mount high-gain antennas. The new Chelton HSD-7000 system uses a phased-array, fuselage-mounted antenna (the HGA-7000) and the HSD-6000 includes the new compact HGA-6000 mechanically steered, tail-mounted antenna, designed to fit smaller airplanes.

The systems share common satcom system components, including the SDU-7300 dual-channel Swift64 satellite data unit and HPA-7400 high-power amplifier. Both can operate independently of aircraft reference systems with the inclusion of the SRU-7200 satcom reference unit. The SDU-7300, which was jointly developed by Chelton and Nera SatCom of Oslo, Norway, provides two Swift64 channels that can be individually configured or bonded to provide a 128-kbps data channel. Chelton said the system is also upgradeable to the next-generation Inmarsat Aero BGAN, which will offer data rates up to 432 kbps. Pricing information for the new line of Chelton HSD equipment has yet to be released.

And it appears that satcom will be coming to classes of aircraft that until recently were deemed unable to accommodate the technology. EMS Technologies said that an AMT-50 multi-channel satcom antenna and HSD-128 high-speed data terminal have been installed aboard a helicopter, a first for the configuration.

TC Communications of Irvine, Calif., performed the installation in a Boeing 234 (civil Chinook) tandem-rotor helicopter for the National Fire Administration of Taiwan, which is used for disaster management and search-and-rescue missions. The NFA added high-speed-data capability to the helicopter so that it could send live video and pictures back to mission control and mobile units on the ground. The video transmission is managed by a TC Communications-built system over the Inmarsat Swift64 service network at 128 kbps.

Assuming satcom antenna technology travels along an evolutionary path that includes smaller, lighter and less expensive equipment, such components could become commonplace. The NASA Glenn Research Center in Cleveland is exploring Ku-band satcom antenna technology, which researchers believe might one day provide a high-speed datalink for Free Flight applications.

NASA’s vision is for data satcom to be used to transmit flight data between all aircraft and ATC, forming a sort of super network where every pilot would know the location and intention of every other aircraft in the vicinity and would broadcast his intentions as well (read ADS-B). Some of the advantages offered by the types of phased-array Ku-band antennas NASA is developing include electronic steering, which requires no moving mechanical parts, higher reliability and high bandwidth capability. In addition, the flat, conformal mechanical design has a lower profile for reduced drag.