In this week, 25 October 1955, the first domestic microwave oven was launched. It is estimated around 95% of homes now own one, but apart from switching it on to nuke a ready-meal, most of us know very little about how they were invented!
The microwave oven heats and cooks food by exposing it to microwave radiation in the electromagnetic spectrum. But believe it or not, it is an appliance born from the radar systems used in World War II and the laboratories of one of the largest US defence companies.
Early in World War II, physicists invented the magnetron, an electron tube that could generate microwaves and help British radar systems to spot Nazi warplanes.
In 1945, Raytheon engineer Percy Spencer accidentally discovered that microwaves from an active radar set he was working on were melting a candy bar in his pocket! He figured out that maybe microwaves could actually cook food. First, he tried deliberately popping popcorn and secondly cooking an egg, which actually exploded in someone’s face!
To verify that microwaves were indeed producing heat, he created a high density electromagnetic field in a metal box which seemed to rapidly increase the temperature of any food placed inside.
Raytheon filed a patent for the microwave cooking process by 1945 and, by 1946, it had built the Radarange, the first microwave oven in the world. The Radarange weighed about 750 pounds and was nearly 6 feet tall, The tubes in the magnetron had to be water-cooled so installation involving plumbing was required. Being as large and heavy as a refrigerator, also meant it was only suitable for commercial use.
The patent was then licensed to Tappan Stove Company who introduced a large 220V wall unit as the first domestic microwave oven on 25 October 1955. However, it was still too large and was prohibitively expensive. Microwave cooking was still viewed with suspicion.
The counter-top microwave we use today was first introduced by Amana Corporation in 1967, at a much lower price, and from then on popularity of the microwave oven grew massively with its introduction into commercial and residential kitchens worldwide. Today, over 30 million microwaves are sold annually!