Short answers, pulled from the story.
The first radome was built in 1941 to protect a rotating radar antenna on a Halifax bomber. This early device known as the H2S system was a desperate measure taken during World War II when engineers realized that exposed antennas were vulnerable to ice, rain, and physical damage from high-speed flight.
Modern radomes are constructed using fiberglass and polytetrafluoroethylene because these materials do not reflect or absorb radio frequencies. The choice of material ensures the structure is solid enough to withstand hurricane-force winds yet transparent enough to let radio waves pass through without distortion.
The E-3 Sentry features a discus-shaped rotodome that spins continuously to provide 360-degree scanning coverage for the radar systems inside. The rotation mechanism must be perfectly balanced to prevent vibrations that could disrupt the radar's precision while allowing the aircraft to detect enemy planes from hundreds of miles away.
The United States Air Force Aerospace Defense Command operated dozens of air defense radar stations across the contiguous United States and Alaska with radomes at least 100 feet in diameter. The Menwith Hill electronic surveillance base in the United Kingdom contains over 30 radomes that prevent observers from seeing the direction of the antennas to conceal which satellites are being targeted.
Walter Bird built the first air-supported radome in 1948 at the Cornell Aeronautical Laboratory. This pneumatic construction used air pressure to maintain its shape and was able to withstand high winds and heavy snow loads while protecting the radar antenna inside.
Radomes can be constructed in spherical, geodesic, and planar shapes depending on the particular application and environment. Spherical radomes are commonly used for stationary antennas while planar radomes are often used on aircraft to reduce drag and protect antennas on large cruise ships and oil tankers.