The MQ-1C Gray Eagle UAV (General Atomics Photo)
The U.S. Army plans to add Ka-band satellite communications capability for its fleet of General Atomics MQ-1C Gray Eagle UAVs, the military service said on Aug. 13.
General Atomics is to award a contract for the Ka-band integration in the first quarter of Fiscal 2020, a timeline that means that the contract award could come by the end of this year.
Todd Smith, the U.S. Army deputy project manager for PEO Aviation's Unmanned Aircraft Systems Project Office in Huntsville, Ala., said that initial operational capability for Ka-band enabled Gray Eagles will be in 2022. The full fleet is to scheduled to have Ka-band capability by 2027.
The military has 10 wideband global satcom (WGS) satellites for the provision of real-time data and video to and from deployed forces and commanders, often in long-range and long-endurance operations.
A number of companies produce Ka-band terminals for aircraft, including Viasat, L3 Harris, Hughes, Honeywell, and Thales.
The Gray Eagle "switch to Ka band datalink allows the fielded units to utilize the WGS system with its high bandwidth capability, and its greater security, reliability and availability than currently used satellite communications systems," said an Army official.
"The overwhelming majority of Ku-band satellites restrict an aircraft's operational area to a single satellite beam, or footprint," the official said. "Ka-band enabled Gray Eagle aircraft operating on WGS extend their range by transiting across WGS's multiple Ka-band spot beams."
Satellite service providers have, at times, argued over the relative merits of Ku-band and Ka-band satellites for military users. Intelsat General Corp., for example, has said that Ku-band is the "incumbent frequency for most deployed UAVs," including the General Atomics' MQ-1 Predator and Gray Eagle and the Northrop Grumman RQ-4 Global Hawk. The company said that such UAVs "can realize substantial increases in throughput on Ku-band" high-throughput satellites (HTS) and that "replacing existing Ku-band antenna with Ka" on one airborne intelligence surveillance and reconnaissance (ISR) platform can cost more than $1 million.
In addition, Intelsat General has said that DoD buying bandwidth on Ka-band satellites, such as WGS and the Inmarsat I-5 constellation, can result in "purchasing many times the bandwidth required for the mission."
"There is no such requirement for Ku-band HTS on the Intelsat Epic platform," according to Intelsat General. "Military users are free to purchase only as much bandwidth as needed, making Ku-band HTS more economical to purchase."
Last September, Chris Hudson, a senior technical advisor with Intelsat General, wrote that while a WGS-approved terminal provides access to some 500 leasable transponder equivalents (TPEs) of 36 MHz worldwide, "it pales next to Ku-band, which has a global supply of over 7000 leasable TPEs."
"Ku-band provides the desired compatibility with an unrivaled depth and breadth of bandwidth options," he wrote. "There are terminals with swap-out kits for C-, X-, Ku- and military Ka-band. Using a kit, an installer can swap a few terminal parts, even while in the field, and convert a terminal from Ku- to Ka-band operations, but this does not qualify as 'seamless switching.'"
But the Army official said that TPEs "are just one of the many important metrics of satcom capacity."
"Other important factors include security, coverage area, availability, and cost," the official said. "A Ka-band enabled Gray Eagle operates in the commercial Ku-band spectrum as well as the military Ka-band spectrum. Having access to both frequency bands provides the platform with a variety of choices."