Military radomes are also found on vehicles carrying radars or SATCOM antennas. For example, a combat aircraft’s nose usually doubles as a radome. This protects the radar and ensures the aircraft’s aerodynamic characteristics are preserved.
Military aircraft may have radomes elsewhere on the fuselage to accommodate airborne surveillance or airborne early warning radars. Ships may have SATCOM antennas underneath radomes. Signals Intelligence gathering ships may have large radomes on their superstructures. These will hide antennas used for collecting COMINT or radar electronic intelligence. Finally, ground military vehicles may have SATCOM antennas beneath small radomes mounted on their bodies.
Purpose & Application
A radome is a covering protecting an antenna used for transmitting radio waves. Usually, radomes cover radar and Satellite Communications (SATCOM) antennas. They serve two purposes. Firstly, they protect the antenna from the environment. While some antennas are designed for prolonged outside use, others may be more sensitive to the elements. As such, they need protection from bright sunlight, wind, rain, dust and precipitation.
Radomes may also help to hide the direction in which an antenna is pointing from outside observation. An uncovered antenna may compromise security at Communications Intelligence (COMINT) facilities. These facilities may have antennas collecting radio signals from satellites through covert eavesdropping. All radio waves travel in a straight line. By seeing the antenna’s direction, it may be possible to discern which satellite the antenna is pointing towards. This may help reveal the identity of a communications satellite a particular nation is eavesdropping on. Such information could be useful to a hostile intelligence service or politically embarrassing to the nation collecting the COMINT. Radomes can also protect people against spinning antennas at ground level.
Radome Design
Due to the properties of radio waves, radomes have specific designs with most using a spherical construction. They use materials which allow the waves to pass through the radome unimpeded. Building a radome out of metal, concrete, wood or brick would be impractical. These materials would be too thick for the radio waves to penetrate.
Radomes predominantly use rigid, air supported or frame designs:
A rigid radome has a self-supporting construction needing no additional reinforcement to support its weight.
An air supported radome cannot support its own weight as it is made from a flexible fabric. The radome retains its shape through a constant interior air pressure keeping it inflated. The disadvantage of the air supported radome is that it needs a constant air supply to remain inflated. This results in expenditure on power and requires backup air systems to be instantly available should the main systems fail. The advantage of the air supported radome is that the material can be thin and provide the least impedance to the radio waves.
Frame radomes use a series of triangular panels arranged to create a spherical shape. The interlocking panels provide a particularly strong structure and are usually found in areas where bad weather is a concern.
There is no perfect radome design. The chosen configuration will depend on the antenna’s characteristics, the local environment, construction considerations and available budget.
