Holmdel Horn Antenna

The Holmdel Horn Antenna is a large microwave horn antenna that was used as a satellite communication antenna and radio telescope during the 1960s at Bell Telephone Laboratories in Holmdel Township, New Jersey, United States. It was designated a National Historic Landmark in 1989 because of its association with the research work of two radio astronomers, Arno Penzias and Robert Wilson. In 1965 while using this antenna, Penzias and Wilson discovered the cosmic microwave background radiation (CMBR) that permeates the universe. This was one of the most important discoveries in physical cosmology since Edwin Hubble demonstrated in the 1920s that the universe was expanding. It provided the evidence that confirmed George Gamow's and Georges Lemaître's "Big Bang" theory of the creation of the universe. This helped change the science of cosmology, the study of the history of the universe, from a field for unlimited theoretical speculation into a discipline of direct observation. In 1978 Penzias and Wilson received the Nobel Prize for Physics for their discovery. The horn antenna at Bell Telephone Laboratories in Holmdel, New Jersey, was constructed in 1959 to support Project Echo, the National Aeronautics and Space Administration's passive communications satellites, which used large aluminized plastic balloons (satellite balloon) as reflectors to bounce radio signals from one point on the Earth to another. The antenna is in length with a radiating aperture of and is constructed of aluminum. The antenna's elevation wheel, which surrounds the midsection of the horn, is in diameter and supports the weight of the structure by means of rollers mounted on a base frame. All axial or thrust loads are taken by a large ball bearing at the narrow apex end of the horn. The horn continues through this bearing into the equipment building or cab. The ability to locate receiver equipment at the horn apex, thus eliminating the noise contribution of a connecting line, is an important feature of the antenna.