The differences between mobile and fixed satellite services are disappearing as fixed antennas get smaller and mobile terminals accommodate higher throughput speeds, according to terminal manufacturers Thrane & Thrane and RaySat Antenna Systems.

While the two sectors still retain their different strengths and weaknesses, both are using new ground technologies such as multi-frequency antennas to encroach on each other’s territory.

“There used to be a black line between MSS and FSS,” said Ron Lockerby, regional sales manager for the Americas for Copenhagen-based Thrane & Thrane Inc. “That line is becoming gray. Inmarsat’s Global Xpress could be a game-changer.”

London-based Inmarsat, which has built its business using L-band satellites for mobile services, is building a new system of Ka-band satellites offering higher speeds for its mobile users starting around 2014.

David Gross, chief executive of RaySat, which was recently purchased by Gilat of Israel and made part of Gilat’s Spacenet Integrated Government Solutions division in the United States, said RaySat is working on phased-array antennas using X- and Ka-band that are small enough to be fitted easily onto vehicles. It will take four to five years for these antennas to be fielded, he said, but when they are, this will usher in an area in which “the antenna finally gets out of the way.”

Lockerby laid out what historically have been the pluses and minuses of fixed versus mobile satellite systems. Fixed systems have higher throughput and lower operating costs than mobile systems as a rule. But fixed satellite services hardware is more expensive and features larger antennas. They are often susceptible to damage from sand, snow or rain.

Mobile systems have smaller antennas, lower hardware costs and broader coverage — near-global with Inmarsat, Iridium and Globalstar. But the cost per minute of use is much higher than fixed satellite systems, and the throughput rates — 492 kilobits per second is as fast as Inmarsat’s BGAN can provide — are far lower than those for fixed satellite systems.

Peter B. de Selding was the Paris bureau chief for SpaceNews.