A radome (which is a portmanteau of radar and dome) is a structural, weatherproof enclosure that protects a radar antenna. The radome is constructed of material that minimally attenuates the electromagnetic signal transmitted or received by the antenna, effectively transparent to radio waves. Radomes protect the antenna from weather and conceal antenna electronic equipment from view. They also protect nearby personnel from being accidentally struck by quickly rotating antennas.
Radomes can be constructed in several shapes - spherical, geodesic, planar, etc. - depending on the particular application, using various construction materials such as fiberglass, polytetrafluoroethylene (PTFE) -coated fabric, and others.
When found on fixed-wing aircraft with forward-looking radar, as are commonly used for object or weather detection, the nose cones often additionally serve as radomes. On aircraft used for airborne early warning and control (AEW & C), a rotating radome, often called a "rotodome", is mounted on the top of the fuselage for 360-degree coverage. Some newer AEW & C configurations instead use three antenna modules inside a radome, usually mounted on top of the fuselage, for 360-degree coverage, such as the Chinese KJ-2000 and Indian DRDO AEW & Cs.
On rotary-wing and fixed-wing aircraft using microwave satellite for beyond-line-of-sight communication, radomes often appear as blisters on the fuselage. In addition to protection, radomes also streamline the antenna system, thus reducing drag.