The R&S SK4105 high-power HF transmitter from Rohde & Schwarz combines high transmission power and reliability with a small footprint, making it ideal for air traffic control over large areas with harsh site conditions, such as Greenland.


In the summer of 2023, Rohde & Schwarz will be delivering low-maintenance and compact R&S SK4105 shortwave transmitters to Naviair, the Danish air navigation service provider that handles air traffic in the lower airspace from the Flight Information Center (FIC) in Greenland.

Greenland’s airspace is huge and transmitter stations are placed in remote locations. Naviair operates several HF and VHF radio systems at strategic points along the Greenlandic coast. The Flight Information Center (FIC) in Nuuk, Greenland, is responsible for primary communications. Its legacy HF transmitters will soon be replaced with the new, high power R&S SK4105 shortwave transmitters.

“The R&S SK4105 is ideal for the demanding Greenland environment with a compact footprint, reduced maintenance, low power consumption and high reliability” Henrik Tvilling Jensen, Project Manager, Naviair. “The new transmitter meets our environmental and performance requirements.”

The R&S SK4105 transmits in the frequency range from 1.5 MHz to 30 MHz with up to 5 kW transmission power. The high transmission power enables clear, long-range radio links between ground stations and aircraft. The transmitter has a liquid cooling pump unit and fits into a 19-inch rack. Other transmitters require up to four times as much space and more frequent maintenance because of mechanical wear.

“Liquid cooling relieves thermal stress on all components in the housing and increases overall system reliability,” explains Marius Münstermann, Vice President Air Traffic Control, Rohde & Schwarz. “This is very important for transmitters with safety-critical tasks, especially those in remote, snow-bound locations that are very difficult to access. Under such operating conditions, waste heat from the transmitter housing can be used to warm the transmitter shelter.”

Compared to air-cooled RF transmitters, overall power requirements are lower. This reduces operating costs and helps air navigation service providers shrink their carbon footprint. In regions outside Greenland's permafrost climate, liquid cooling has another benefit: since the cooling system is independent of ambient air, the transmitter can also be operated in locations with little air conditioning.

“The R&S SK4105 control transmitter is based on R&S Series 4100 radio devices, whose 1kW version has been successfully used in several Greenland coastal radio stations for vessel traffic,” Mr. Münstermann says. “The exciter is in line with EUROCAE ED-137C criteria and is software defined, making it easier to integrate new transmitter functions and adapt to future radio standards. As part of the Rohde & Schwarz CERTIUM portfolio, the HF high-power transmitter is compatible with other CERTIUM hardware and software and can be expanded to suit specific applications.”