The
Horn AntennaThe Horn Antenna, at Bell Telephone Laboratories in Holmdel, New Jersey, is listed as a National Historic Landmark because of its association with the research work of two radio astronomers, Arno Penzias and Robert Wilson. In 1965 while using the Horn Antenna, Penzias and Wilson stumbled on the...
, at
Bell Telephone LaboratoriesBell Laboratories is the research and development organization of Alcatel-Lucent and previously of the American Telephone & Telegraph Company .Bell Laboratories has had its headquarters at Murray Hill, New Jersey, and it has research and development facilities...
in Holmdel, New Jersey, is listed as a
National Historic LandmarkA National Historic Landmark is a building, site, structure, object, or district, that is officially recognized by the United States government for its historical significance. All NHLs are listed in the National Register of Historic Places...
because of its association with the research work of two radio astronomers, Arno Penzias and
Robert WilsonFor the American President, see Woodrow Wilson.Robert Woodrow Wilson is an American astronomer, Nobel laureate in physics, who with Arno Allan Penzias discovered in 1964 the cosmic microwave background radiation...
. In 1965 while using the Horn Antenna, Penzias and Wilson stumbled on the microwave background radiation that permeates the universe. Cosmologists quickly realized that Penzias and Wilson had made the most important discovery in modern astronomy since
Edwin HubbleEdwin Powell Hubble was an American astronomer. He profoundly changed our understanding of the universe by demonstrating the existence of other galaxies besides the Milky Way. He also discovered that the degree of redshift observed in light coming from a galaxy increased in proportion to the...
demonstrated in the 1920s that the universe was expanding.
The
Horn AntennaThe Horn Antenna, at Bell Telephone Laboratories in Holmdel, New Jersey, is listed as a National Historic Landmark because of its association with the research work of two radio astronomers, Arno Penzias and Robert Wilson. In 1965 while using the Horn Antenna, Penzias and Wilson stumbled on the...
, at
Bell Telephone LaboratoriesBell Laboratories is the research and development organization of Alcatel-Lucent and previously of the American Telephone & Telegraph Company .Bell Laboratories has had its headquarters at Murray Hill, New Jersey, and it has research and development facilities...
in Holmdel, New Jersey, is listed as a
National Historic LandmarkA National Historic Landmark is a building, site, structure, object, or district, that is officially recognized by the United States government for its historical significance. All NHLs are listed in the National Register of Historic Places...
because of its association with the research work of two radio astronomers, Arno Penzias and
Robert WilsonFor the American President, see Woodrow Wilson.Robert Woodrow Wilson is an American astronomer, Nobel laureate in physics, who with Arno Allan Penzias discovered in 1964 the cosmic microwave background radiation...
. In 1965 while using the Horn Antenna, Penzias and Wilson stumbled on the microwave background radiation that permeates the universe. Cosmologists quickly realized that Penzias and Wilson had made the most important discovery in modern astronomy since
Edwin HubbleEdwin Powell Hubble was an American astronomer. He profoundly changed our understanding of the universe by demonstrating the existence of other galaxies besides the Milky Way. He also discovered that the degree of redshift observed in light coming from a galaxy increased in proportion to the...
demonstrated in the 1920s that the universe was expanding. This discovery provided the evidence that confirmed
George GamowGeorge Gamow , born Georgiy Antonovich Gamov , was a Russian Empire-born theoretical physicist and cosmologist...
's and Abbe Georges Lemaitre's "Big Bang" theory of the creation of the universe and forever changed the science of cosmology — the study of the history of the universe — from a field for unlimited theoretical speculation into a subject disciplined by direct observation. In 1978 Penzias and Wilson received the Nobel Prize for Physics for their momentous discovery.
Description
The Horn Antenna at Bell Telephone Laboratories in Holmdel, New Jersey, was constructed in 1959 to support
Project EchoThe Echo satellites were NASA's first passive communications satellite experiment. Each spacecraft was designed as a metallized balloon satellite acting as a passive reflector of microwave signals...
—the National Aeronautics and Space Administration's passive communications satellite project.
The antenna is 50 feet (15 m) in length with a radiating aperture of 20 by 20 feet (6 by 6 m) and is made of aluminum. The antenna's elevation wheel is 30 feet (10 m) 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 apex end of the horn. The horn continues through this bearing into the equipment cab. The ability to locate receiver equipment at the apex of the horn, thus eliminating the noise contribution of a connecting line, is an important feature of the antenna. A radiometer for measuring the intensity of radiant energy is found in the equipment cab.
The triangular base frame of the antenna is made from structural steel. It rotates on wheels about a center pintle ball bearing on a track 30 feet (10 m) in diameter. The track consists of stress-relieved, planed steel plates which are individually adjusted to produce a track flat to about 1/64 inch (0.4 mm). The faces of the wheels are cone-shaped to minimize sliding friction. A tangential force of 100 pounds force (400 N) is sufficient to start the antenna in motion.
To permit the antenna beam to be directed to any part of the sky, the antenna is mounted with the axis of the horn horizontal. Rotation about this axis affords tracking in elevation while the entire assembly is rotated about a vertical axis for tracking in the azimuth.
With the exception of the steel base frame, which was made by a local steel company, the antenna was fabricated and assembled by the Holmdel Laboratory shops under the direction of Mr. H. W. Anderson, who also collaborated on the design. Assistance in the design was also given by Messrs. R. O'Regan and S. A. Darby. Construction of the antenna was completed under the direction of Mr. A. B.
Crawford- In Canada :* Crawford Bay Airport, British Columbia* Crawford Lake Conservation Area, Ontario- In the United Kingdom :* Crawford, a small village near Rainford, Merseyside* Crawford, South Lanarkshire, Scotland home to …...
from
Freehold Borough, New JerseyFreehold Borough is a Borough in Monmouth County, New Jersey, United States. As of the United States 2000 Census, the borough population was 10,976. It is the county seat of Monmouth County....
.
When not in use, the antenna azimuth sprocket drive is disengaged, thus permitting the structure to "weathervane" and seek a position of minimum wind resistance. The antenna was designed to withstand winds of 100 miles per hour (160 km/h) and the entire structure weighs 18 tons.
The Horn Antenna combines several ideal characteristics: it is extremely broad-band, has calculable aperture efficiency, and the back and sidelobes are so minimal that scarcely any thermal energy is picked up from the ground. Consequently it is an ideal radio telescope for accurate measurements of low levels of weak background radiation.
A plastic clapboarded utility shed 10 by 20 feet (3 by 6 m), with two windows, a double door and a sheet metal roof, is located next to the Horn Antenna. This structure houses equipment and controls for the Horn Antenna and is included as a part of the designation of U.S. National Historic Landmark. It is not in use anymore.
Footnotes
The original material in this article was taken from a
National Park ServiceThe National Park Service is the U.S. federal agency that manages all national parks, many national monuments, and other conservation and historical properties with various title designations...
publication which in turn used the following sources:
-
- Richard Learner, Astronomy Through the Telescope (New York: Van Nostrand Reinhold Company, 1981), p. 154.
-
- A.B. Crawford, D. C. Hogg, and L. E. Hunt, "Project Echo: A Horn Antenna for Space Communication," Bell System Technical Journal (July 1961), pp. 1095-1099.
- Aaronson, Steve. "The Light of Creation: An Interview with Arno A. Penzias and Robert W. Wilson." Bell Laboratories Record. January 1979, pp. 12-18.
- Abell, George O. Exploration of the Universe. 4th ed., Philadelphia: Saunders College Publishing, 1982.
- Asimov, Isaac. Asimov's Biographical Encyclopedia of Science and Technology. 2nd ed., New York: Doubleday & Company, Inc., 1982.
- Bernstein, Jeremy. Three Degrees Above Zero: Bell Labs in the Information Age. New York: Charles Scribner's Sons, 1984.
- Chown, Marcus. "A Cosmic Relic in Three Degrees," New Scientist, September 29, 1988, pp. 51-55.
- Crawford, A.B., D.C. Hogg and L.E. Hunt. "Project Echo: A Horn-Reflector Antenna for Space Communication," The Bell System Technical Journal, July 961, pp. 1095-1099.
- Disney, Michael. The Hidden Universe. New York: Macmillan Publishing Company, 1984.
- Ferris, Timothy. The Red Limit: The Search for the Edge of the Universe. 2nd ed., New York: Quill Press, 1978.
- Friedman, Herbert. The Amazing Universe. Washington, DC: National Geographic Society, 1975.
- Hey, J.S. The Evolution of Radio Astronomy. New York: Neale Watson Academic Publications, Inc., 1973.
- Jastrow, Robert. God and the Astronomers. New York : W. W. Norton & Company, Inc., 1978.
- H.T. Kirby-Smith U.S. Observatories: A Directory and Travel Guide. New York: Van Nostrand Reinhold Company, 1976.
- Learner, Richard. Astronomy Through the Telescope. New York: Van Nostrand Reinhold Company, 1981.
- Penzias, A.A., and R. W. Wilson. "A Measurement of the Flux Density of CAS A At 4080 Mc/s," Astrophysical Journal Letters, May 1965, pp. 1149-1154.
External links