William H. Doherty was an American electrical engineer noted for his invention of the Doherty amplifier

Doherty amplifier

The Doherty amplifier is a modified class C radio frequency amplifier invented by William H. Doherty in 1936.The amplifier is usually configured as a grounded-cathode, carrier-peak amplifier...

.

Doherty was born in Cambridge, Massachusetts

Cambridge, Massachusetts

Cambridge is a city in Middlesex County, Massachusetts, United States, in the Greater Boston area. It was named in honor of the University of Cambridge in England, an important center of the Puritan theology embraced by the town's founders. Cambridge is home to two of the world's most prominent...

, received his B.S. degree in electrical communication engineering in 1927 and M.S. degree in engineering in 1928, both from Harvard University

Harvard University

Harvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...

. After a few months in the American Telephone and Telegraph Company Long Lines Department in Boston, he joined the National Bureau of Standards to study radio phenomena. In 1929 he began work at Bell Telephone Laboratories where he developed high power radio transmitters for transoceanic radio telephones and broadcasting.

In 1936 he invented a means to greatly improve the efficiency of RF power amplifiers, quickly termed the "Doherty amplifier". It was first used in a 500-kilowatt transmitter made by Western Electric Company for WHAS

WHAS (AM)

WHAS, known by the on air branding as "84 WHAS", is an AM radio station broadcasting in Louisville, Kentucky. It is a 50,000 Watt clear channel radio station assigned to frequency 840 kHz. With clear channel status, its nighttime signal can be heard in most of the continental U.S...

, Louisville, Kentucky

Louisville, Kentucky

Louisville is the largest city in the U.S. state of Kentucky, and the county seat of Jefferson County. Since 2003, the city's borders have been coterminous with those of the county because of a city-county merger. The city's population at the 2010 census was 741,096...

, but the Federal Communications Commission

Federal Communications Commission

The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...

 restricted broadcast stations to 50 kilowatts maximum power. By 1940 Western Electric had incorporated Doherty amplifiers in 35 commercial radio stations worldwide.

Doherty received the 1937 IEEE Morris N. Liebmann Memorial Award

IEEE 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...

 for his improvement in the efficiency of radio-frequency power amplifiers.

Selected works

• "A new high efficiency power amplifier for modulated waves", Proc. IRE, vol. 24, pages 1163-1182. September 1936.