History of the Home Microwave

Theories that high-frequency electric fields could be used for heating developed as early as 1933 when Westinghouse demonstrated a 10-kilowatt shortwave radio transmitter that cooked steaks and potatoes between two metal plates at the World's Fair in Chicago. However, this method used frequencies that are lower than those of microwaves.

Image: Short Wave Craft magazine, Popular Book Corp., New York, Vol. 4, No. 7, November 1933, p. 394. Retrieved March 21, 2015 from http://www.americanradiohistory.com. Last accessed June 28, 2021.

John Randall and Harry Boot invented the cavity magnetron tube at Birmingham University in England. The magnetron tube became very important during World War II, and was used by the Allied forces to emit microwave radar signals to detect distant, Nazi aircraft and ships.

Image: Hind, Angela. "Briefcase 'that changed the world.'" BBC Radio 4's The World in a Briefcase, February 5, 2007. Last accessed June 28, 2021, http://news.bbc.co.uk/2/hi/science/nature/6331897.stm.

While working on a powered radar set, Raytheon engineer, Percy Spencer, discovered that microwaves emitted by the magnetron melted the chocolate in his pocket. He experimented with popcorn kernels by directing the magnetron tube at them, resulting in the first microwaved popcorn.

Percy Spencer filed for the first microwave oven patent - Method of treating foodstuffs (U.S. Patent 2495429A).

Image: Spencer, P.L. "Prepared Food, Article and Method of Preparation." U.S. Patent Office, August 30, 1949. Retrieved June 28, 2021 from https://spectrum.ieee.org/tech-history/space-age/a-brief-history-of-the-microwave-oven.

The first commercial microwave - the Radarange - was sold by Raytheon for $5000 ($51,000 in today's dollar), was six feet tall, weighed over a third of a tonne and used 3000 Watts of power. The massive microwaves were only used by restaurants, ship's galleys and large canteens.

Image: Ackermann, Evan. "A Brief History of the Microwave Oven." IEEE Spectrum, September 30, 2016. Last accessed, June 27, 2021, https://spectrum.ieee.org/tech-history/space-age/a-brief-history-of-the-microwave-oven.

The first microwave oven designed for consumers was offered by Tappan. The Tappan RL-1 was wall mounted and cost US $1,295 (almost $11,000 today).

Image: Ackermann, Evan. "A Brief History of the Microwave Oven." IEEE Spectrum, September 30, 2016. Last accessed, June 27, 2021, https://spectrum.ieee.org/tech-history/space-age/a-brief-history-of-the-microwave-oven.

In the 1960s, Litton Industries developed a new configuration of the microwave that was a short, wide shape and used a magnetron feed which allowed for oven to survive a no-load condition when it had no food to absorb the waves. This configuration is still used today.

in 1967, Litton would go on to buy Stouffer Food Corp. one of the original frozen meal companies. Invented in the 1950s, TV dinners and frozen meals were starting to become more and more popular. Litton utilized Stouffer's frozen meals as a way to sell their microwave ovens.

Amana Refridgeration (a Raytheon subsidiary) created the Amana Radaranges - a domestic counter-top version that sold for $495.

Image: "Welcome to Radarange Central." Last accessed June 28, 2021, https://www.radarange.com/#QA.

In March 1973, the Consumer Union issued a warning regarding the potential harmful effects of microwave radiation. The government and industry were quick to answer and assert the safety of their product. While the Consumer Union's concerns were unsubstantiated, it did lead to RF radiation safety standards were use today.

The microwave as a common household appliance continued to grow in popularity, and by 1986 25% of household owned a microwave. This same year, the microwave safe tray was also invented, so frozen meal companies, like Swanson's, could now be cooked via microwave. By 1997, 90% of American household will own a microwave.