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.
It was first used in a 500-kilowatt transmitter made by Western Electric Company and proposed for WHAS, Louisville, Kentucky, but the Federal Communications Commission restricted broadcast stations to 50 kilowatts maximum power, and WHAS would go on to install a 50,000 watt Western Electric Doherty transmitter.
By 1940 Western Electric had incorporated Doherty amplifiers in 35 commercial radio stations worldwide, nearly all of these at the 50,000 watt level, and employing a 5,000 watt driver of conventional design.
Doherty received the 1937 IEEE Morris N. Liebmann Memorial Award for his improvement in the efficiency of radio-frequency power amplifiers.