What Is Military SATCOM?

Military Satellite Communications (Mil SATCOM) is a specialised system where satellites transmit signals back and forth for long-distance, secure communication.

The scale and complexity of military operations rely on sophisticated communication systems to operate across land, sea, and air. SATCOM is used on military vehicles, aircraft and with defence equipment such as portable computers or terminals.

Military SATCOM is built specifically for deployed forces to communicate over long distances and bypass obstructions along the distance that limit communication lines.

Operational Frequency 

Radio waves are electromagnetic radiation waves that travel in a straight line. They enable communication over distances, but not all types of radio waves can travel along the Earth’s curvature.

For radio waves to be effective, the antenna transmitting the radio signals needs to have a clear path to the receiving radio. The distance radio waves can reach depends on the height of the antenna. For example, a radio antenna two metres above the ground can transmit and receive signals from a distance of around six kilometres. The higher the antenna, the more range it can cover. 

This said, an antenna placed on a higher plane such as a building doesn’t guarantee that radio waves will reach the receiver. Urban areas present a challenge as other buildings can block the signal. The same blockage can occur from surrounding hills in the vicinity of the signal. Trees and dense forests can also limit radio signals in natural spaces.

Obstructions along the path of the signal will not necessarily stop it from reaching the recipient. The signal might still reach its destination, but the connection will be weak or distorted. In a military environment, a weak signal impedes clear, timely communication, which can put personnel and operations at serious risk.

The Role Of SATCOM In Defence

Military operations require robust radio signals that can reach long distances, whether for communication on military transport or with defence equipment. SATCOM achieves this by transmitting radio traffic into a satellite in space above the Earth’s orbit. Radio waves going up towards a satellite in space avoid obstacles along their path on the ground. When the signal reaches the satellite, it’s sent back down to the recipient on Earth.

Satellite communication gets around this by sending signals back and forth through space to reach intercontinental locations, making it possible to avoid obstacles that can impact short-range radio signals. SATCOM makes international communication possible because it’s not limited by the Earth’s curvature. Communicating via radio signals from New York to London without a satellite would require an antenna 2.6 million feet (800,000m) high! 

How Does SATCOM Work? 

Satellite communication uses satellites in space and stations on the ground to send and receive information using microwaves between two locations on Earth. SATCOM has three stages: the uplink, transponder and downlink. 

Transmitting a signal is the “uplink”. When the signal is picked up by the orbiting satellite, its strength is amplified to change its frequency. The signal is then relayed back to the designated station on Earth – this is the “transponder” stage.

Finally, transmitters send signals (single or multiple) to points around the globe – this is the “downlink” stage.

SATCOM Frequency Bands  

Similar to radio waves, SATCOM has various frequency bands. The International Telecommunications Union (ITU) has specific frequencies reserved for military and government communications. The most commonly used bands used for SATCOM include S-, C-, L-, X-, Ka-, and Ku-band. These high-frequency bands also have sub-bands, which are often used in SATCOM.

Each band has its advantages and disadvantages. Some bands can transmit a heavy stream of traffic, while others are sensitive to weather disruptions. In contrast, some bands can withstand bad weather but can only transmit narrowband communications. Military equipment also differs for each band. Specific bands require a SATCOM antenna that’s larger and better suited for static.

Some bands are solely designated for military use. These include the X-band frequencies, although other wavebands are added to avoid congestion on certain bands. The choice of frequency band is determined by the geographic area where the signal is sent or received, as well as the power required to send the signal back and forth.

SATCOM Is Critical In Defence 

Military SATCOM is at the core of relaying and receiving mission-critical information in time without interference. Radio waves transmit in a straight line, and can be weakened by obstacles along the signal’s trajectory. SATCOM gets around obstacles by sending signals to and from a space satellite to remove interference. 

Satellite communication in defence environments covers a range of purposes. Some satellites are only used for military operations. Others are designated for government communication and some are privately owned for SATCOM services.

SATCOM, like radio waves, has its own frequencies, but only certain bands are designated for military (e.g. X-band). The type of band used depends on the location of the operation, the nature of the communication transmitted, and how the satellite is powered. Military communication demands high levels of security and agility for its complex operations. This means SATCOM is deployed on military vehicles, submarines, naval ships, and aircraft. 

Forces rely on SATCOM for stable communication between headquarters and forces in tactical and strategic locations via portable devices like military phones. In this way, SATCOM relays messages across vast geographical areas that would otherwise be inaccessible.