Microwave

The exploitation of high-frequency radio waves for heating substances was made possible by the development of vacuum tube radio transmitters.

1920

By 1930 the application of short waves to heat human tissue had developed into the medical therapy of diathermy.

1930

At the 1933 Chicago World's Fair, Westinghouse demonstrated the cooking of foods between two metal plates attached to a 10 kW, 60 MHz shortwave transmitter.

1933

The 1937 United States patent application by Bell Laboratories states:[4]

1937

This invention relates to heating systems for dielectric materials and the object of the invention is to heat such materials uniformly and substantially simultaneously throughout their mass. ... It has been proposed therefore to heat such materials simultaneously throughout their mass by means of the dielectric loss produced in them when they are subjected to a high voltage, high frequency field.

In 1945, the heating effect of a high-power microwave beam was accidentally discovered by Percy Spencer, an American self-taught engineer from Howland, Maine.

1945

On 8 October 1945, Raytheon filed a United States patent application for Spencer's microwave cooking process, and an oven that heated food using microwave energy from a magnetron was soon placed in a Boston restaurant for testing.

Oct 8, 1945

In 1947, Raytheon built the "Radarange", the first commercially available microwave oven.

1947

Raytheon licensed its technology to the Tappan Stove company of Mansfield, Ohio in 1952

1952

In the 1960s,[specify] Litton bought Studebaker's Franklin Manufacturing assets, which had been manufacturing magnetrons and building and selling microwave ovens similar to the Radarange.

1960

Japan's Sharp Corporation began manufacturing microwave ovens in 1961.

1961

Between 1964 and 1966, Sharp introduced the first microwave oven with a turntable, a feature that promotes convenient even heating of food.

Period: 1964 to 1966

In 1967, they introduced the first popular home model, the countertop Radarange, at a price of US$495 ($4,000 in 2019 dollars).

1967

By 1972, Litton (Litton Atherton Division, Minneapolis) introduced two new microwave ovens, priced at $349 and $399, to tap into the market estimated at $750 million by 1976, according to Robert I Bruder, president of the division.[17]

1972

Sales volume of 40,000 units for the U.S. industry in 1970 grew to one million by 1975.

1975

In Canada, fewer than 5% of households had a microwave oven in 1979, but more than 88% of households owned one by 1998

1979

After Japanese dominance for much of the 1980s, with Sharp as market leader, South Korean manufacturers began entering the market in the late 1980s, with Samsung becoming a major microwave manufacturer.[18]

1980

. By 1986, roughly 25% of households in the U.S. owned a microwave oven, up from only about 1% in 1971;[19] the U.S. Bureau of Labor Statistics reported that over 90% of American households owned a microwave oven in 1997.

1997

In France, 40% of households owned a microwave oven in 1994, but that number had increased to 65% by 2004.[23]

2004

The microwave is still becoming better and will be for a long time.

2020