Raytheon introduced the first commercial microwave oven, the Radarange, in 1947. The machine grew out of Raytheon engineer Percy Spencer’s work with magnetrons, the high-powered vacuum tubes used to generate microwaves for radar.
In 1945, Spencer noticed that radiation from an operating radar magnetron had melted a candy bar in his pocket. He tested the effect with popcorn and an egg, then created a metal enclosure that concentrated microwave energy to heat food. Raytheon patented the cooking process and tested an early oven in a Boston restaurant before developing the Radarange.
The original commercial unit was dramatically different from a modern countertop appliance. It stood about 1.8 metres tall, weighed roughly 340 kilograms, consumed 3 kilowatts and cost between $2,000 and $3,000. It also required water cooling. Raytheon later licensed the technology to Tappan for home use, while Amana’s 1967 countertop model helped make microwave cooking practical for households.