A radar dome is a spherical shell that encloses a radar device. Radar domes are often used to protect sensitive radar equipment from the elements. They may also be used to protect people working in the area of rotating radar dishes. In radar systems used for surveillance, a dome may be installed to deliberately obscure the radar scanning direction. Aircraft that have an external radar attachment use a radar dome to streamline surfaces exposed to air friction.
Radar devices can be used to identify the distance, direction and speed of physical objects that may not be visible to the naked eye. Air traffic control and weather forecasting routinely use radar devices to scan the skies. Radar operates by sending a radio wave, a form of electromagnetic radiation, towards an object and then waiting for the signal to bounce back. The time delay of the signal’s return indicates the distance of an object in the scanning direction. Changes in the signal’s frequency specify the relative velocity of the object.
To collect some of the returning radio waves, which are reflected in all directions by objects, radar devices often need to use a sizable radar dish. The dish directs incoming radio waves to a receiver, where they can be analyzed. Radar dishes typically need to be free of dirt, rain and ice to function properly, however. They may also need to remain still and thus be protected from the wind. Providing this sort of protection to radar dishes and their associated electronics is one function of the radar dome.
Radar devices that use dishes need to be aimed in the direction of interest. Many applications of radar technology require coverage in all directions; this is understandable in the case of air traffic control. Therefore, many radar devices are able to rotate to aim in a specific direction. This movement, which can be rapid, may present a danger to people in the vicinity of the moving radar dish. Keeping people away from a moving dish is another function of the radar dome.
Some aircraft use onboard radar technology to scan airspaces and identify ground objects during the night. The equipment, which is mounted on an aircraft’s exterior, would not be very aerodynamic without an enclosure surrounding it. An enclosure of this type may resemble half of a radar dome, but would more likely adopt the highly-aerodynamic tear drop shape. Without a smooth, aerodynamic enclosure, air friction would slow down an aircraft as well as put excessive mechanical stress on radar equipment.