Harald T. Friis
Encyclopedia
Harald Trap Friis who published as H. T. Friis, was a noted Danish-American radio
engineer whose work at Bell Laboratories included pioneering contributions to radio propagation
, radio astronomy
, and radar
. His two Friis formulas remain widely used.
, enmark]. In 1916 received his electrical engineering degree from the Royal Technical College, Copenhagen
. After a stint at the Royal Gun Factory, in 1919 he received a Columbia University
fellowship to study radio engineering under John H. Morecroft. In 1920 Friis joined a Western Electric Company research group which in 1925 became part of Bell Laboratories. There he remained for his entire professional career.
(IRE) paper on radio transmission measurements, 1925 IRE paper on directional antennas, and 1928 IRE paper on oscillographic observations of propagation phenomena. These papers documented studies of field strength and noise over a wide range of frequencies and stressed the importance of the signal to noise ratio (SNR) in receivers rather than simple field strength.
During the early 1930s Friis helped design the radio receiver used by Karl Jansky
for radio astronomy
, and with Edmond Bruce
invented the rhombic antenna
widely used for shortwave communications. In 1938 Friis became the director of the Holmdel Radio Laboratory developing microwave
systems, where he and Alfred C. Beck designed a horn reflector antenna; AT&T
's national microwave relay network was subsequently based on this work. During World War II, Friis invented a "rocking horse" mechanical scanner for radar used to locate enemy mortars. He also authorized research into the first germanium diodes (Teal
, 1942).
In 1946 Friis published his well-known analytic formula for transmission loss, the Friis transmission equation
, which is still widely employed. In 1958 he retired but continued as a research consultant to the Hewlett-Packard Company as a friend of David Packard
. He held 31 U.S. patents.
Friis died on June 15, 1976, at age 83, of a stroke in Palo Alto, California
.
in 1939, the Valdemar Poulsen Medal
of the Royal Danish Academy of Sciences and Letters
in 1954, the IRE Medal of Honor (now the IEEE Medal of Honor
) in 1955, the Ballentine Medal from the Franklin Institute
in 1958 and the Mervin Kelly Award of the IEEE in 1964.
Radio
Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...
engineer whose work at Bell Laboratories included pioneering contributions to radio propagation
Radio propagation
Radio propagation is the behavior of radio waves when they are transmitted, or propagated from one point on the Earth to another, or into various parts of the atmosphere...
, radio astronomy
Radio astronomy
Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies. The initial detection of radio waves from an astronomical object was made in the 1930s, when Karl Jansky observed radiation coming from the Milky Way. Subsequent observations have identified a number of...
, and radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
. His two Friis formulas remain widely used.
Background
Friis was born in NaestvedNaestved
Næstved a commercial town in a municipality of the same name, lies on the island of Zealand in Denmark. The town is one hour's travel from Copenhagen. Næstved has a population of 41,667 . Næstved's UN/LOCODE is DKNVD....
, enmark]. In 1916 received his electrical engineering degree from the Royal Technical College, Copenhagen
Copenhagen
Copenhagen is the capital and largest city of Denmark, with an urban population of 1,199,224 and a metropolitan population of 1,930,260 . With the completion of the transnational Øresund Bridge in 2000, Copenhagen has become the centre of the increasingly integrating Øresund Region...
. After a stint at the Royal Gun Factory, in 1919 he received a Columbia University
Columbia University
Columbia University in the City of New York is a private, Ivy League university in Manhattan, New York City. Columbia is the oldest institution of higher learning in the state of New York, the fifth oldest in the United States, and one of the country's nine Colonial Colleges founded before the...
fellowship to study radio engineering under John H. Morecroft. In 1920 Friis joined a Western Electric Company research group which in 1925 became part of Bell Laboratories. There he remained for his entire professional career.
Career
Friis' first important publications were his 1923 Institute of Radio EngineersInstitute of Radio Engineers
The Institute of Radio Engineers was a professional organization which existed from 1912 until January 1, 1963, when it merged with the American Institute of Electrical Engineers to form the Institute of Electrical and Electronics Engineers .-Founding:Following several attempts to form a...
(IRE) paper on radio transmission measurements, 1925 IRE paper on directional antennas, and 1928 IRE paper on oscillographic observations of propagation phenomena. These papers documented studies of field strength and noise over a wide range of frequencies and stressed the importance of the signal to noise ratio (SNR) in receivers rather than simple field strength.
During the early 1930s Friis helped design the radio receiver used by Karl Jansky
Karl Guthe Jansky
Karl Guthe Jansky was an American physicist and radio engineer who in August 1931 first discovered radio waves emanating from the Milky Way. He is considered one of the founding figures of radio astronomy.- Early life :...
for radio astronomy
Radio astronomy
Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies. The initial detection of radio waves from an astronomical object was made in the 1930s, when Karl Jansky observed radiation coming from the Milky Way. Subsequent observations have identified a number of...
, and with Edmond Bruce
Edmond Bruce
Edmond Bruce was an American radio pioneer best known for creating the rhombic antenna and Bruce array.Bruce was born in Saint Louis, Missouri, and raised in Cambridge, Massachusetts, Brooklyn, and Washington, D.C...
invented the rhombic antenna
Rhombic antenna
A rhombic antenna is a broadband directional antenna co-invented by Edmond Bruce and Harald Friis, mostly commonly used in HF ranges.- Technical Detail :...
widely used for shortwave communications. In 1938 Friis became the director of the Holmdel Radio Laboratory developing microwave
Microwave
Microwaves, a subset of radio waves, have wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz and 300 GHz. This broad definition includes both UHF and EHF , and various sources use different boundaries...
systems, where he and Alfred C. Beck designed a horn reflector antenna; AT&T
AT&T
AT&T Inc. is an American multinational telecommunications corporation headquartered in Whitacre Tower, Dallas, Texas, United States. It is the largest provider of mobile telephony and fixed telephony in the United States, and is also a provider of broadband and subscription television services...
's national microwave relay network was subsequently based on this work. During World War II, Friis invented a "rocking horse" mechanical scanner for radar used to locate enemy mortars. He also authorized research into the first germanium diodes (Teal
Gordon K. Teal
Gordon Kidd Teal invented a method of applying the Czochralski method to produce extremely pure germanium single crystals used in making greatly improved transistors. He, together with Morgan Sparks invented a modification of the process that produced the configuration necessary for the...
, 1942).
In 1946 Friis published his well-known analytic formula for transmission loss, the Friis transmission equation
Friis transmission equation
The Friis transmission equation is used in telecommunications engineering, and gives the power received by one antenna under idealized conditions given another antenna some distance away transmitting a known amount of power. The formula was derived in 1945 by Danish-American radio engineer Harald T...
, which is still widely employed. In 1958 he retired but continued as a research consultant to the Hewlett-Packard Company as a friend of David Packard
David Packard
David Packard was a co-founder of Hewlett-Packard , serving as president , CEO , and Chairman of the Board . He served as U.S. Deputy Secretary of Defense from 1969–1971 during the Nixon administration...
. He held 31 U.S. patents.
Friis died on June 15, 1976, at age 83, of a stroke in Palo Alto, California
Palo Alto, California
Palo Alto is a California charter city located in the northwest corner of Santa Clara County, in the San Francisco Bay Area of California, United States. The city shares its borders with East Palo Alto, Mountain View, Los Altos, Los Altos Hills, Stanford, Portola Valley, and Menlo Park. It is...
.
Awards
Friis received the IRE Morris N. Liebmann AwardIEEE Morris N. Liebmann Memorial Award
The initially called Morris Liebmann Memorial Prize provided by the Institute of Radio Engineers , the IEEE Morris N. Liebmann Memorial Award was created in 1919 in honor of Colonel Morris N. Liebmann. It was initially given to awardees who had "made public during the recent past an important...
in 1939, the Valdemar Poulsen Medal
Valdemar Poulsen
Valdemar Poulsen was a Danish engineer who developed a magnetic wire recorder in 1899.-Biography:He was born on 23 November 1869 in Copenhagen...
of the Royal Danish Academy of Sciences and Letters
Royal Danish Academy of Sciences and Letters
Royal Danish Academy of Sciences and Letters is a Danish non-governmental science Academy, founded 13 November 1742 by permission of the King Christian VI, as a historical Collegium Antiquitatum...
in 1954, the IRE Medal of Honor (now the IEEE Medal of Honor
IEEE Medal of Honor
The IEEE Medal of Honor is the highest recognition of the Institute of Electrical and Electronics Engineers . It has been awarded since 1917, when its first recipient was Major Edwin H. Armstrong. It is given for an exceptional contribution or an extraordinary career in the IEEE fields of...
) in 1955, the Ballentine Medal from the Franklin Institute
Franklin Institute
The Franklin Institute is a museum in Philadelphia, Pennsylvania, and one of the oldest centers of science education and development in the United States, dating to 1824. The Institute also houses the Benjamin Franklin National Memorial.-History:On February 5, 1824, Samuel Vaughn Merrick and...
in 1958 and the Mervin Kelly Award of the IEEE in 1964.
Selected works
- Seventy Five Years in an Exciting World (1971)
- Antennas: Theory and Practice (1952)
- Proc. IRE, vol. 34, p. 254 (Friis transmission equationFriis transmission equationThe Friis transmission equation is used in telecommunications engineering, and gives the power received by one antenna under idealized conditions given another antenna some distance away transmitting a known amount of power. The formula was derived in 1945 by Danish-American radio engineer Harald T...
)(1946) - A New Directional Receiving System (1925)
- High fFequency Amplifiers (1924)
Other sources
- Pierce, John Robinson The Wisdom of Harald Friis (1957)
- Teal, Gordon K.Gordon K. TealGordon Kidd Teal invented a method of applying the Czochralski method to produce extremely pure germanium single crystals used in making greatly improved transistors. He, together with Morgan Sparks invented a modification of the process that produced the configuration necessary for the...
Single Crystals of Germanium and Silicon—Basic to the Transistor and Integrated Circuit (IEEE Transactions on Electron Devices, vol. ED-23, no. 7, July 1976)