An ad for the Magic Chef Microwave Oven

Who Invented the Microwave Oven? (and it was an accident!)

Hello there! It’s been awhile. As you may remember (or maybe it’s your first visit), I recently bought a house, then I spent too much time and money to make it habitable. Now, I finally live in it, and I have a new microwave oven. Weirdly, using it is less intuitive than the ones I’m used to. This led me to read the manual and to ask who could have come up with it.

Who Created the Microwave Oven?

Apparently, it was an accident. Quite a useful one, if you ask me (apparently, 90% of people in America have one!). But let’s travel back in time, to 1945.

Then, there was an American engineer and inventor who worked for the defense technology company called the Raytheon Corporation. His name was Percy Spencer and, as World War II went on, he was developing a radar, a microwave radar transmitter!

As the story goes, Spencer was experimenting on his radar magnetron. When he noticed that a candy bar in his pocket had melted, he quickly made the connection with the magnetron he stood in front of. This was radar tech, not food tech, but one became the other as the microwaves emitted by the magnetron turned out to be useful to cook.

Of course, this was just the spark needed to develop a real invention, experimentations were required to be made in order to see how to really use the microwaves to properly heat food. At first, Spencer used an egg, but the resulting explosion led him to go with corn kernels. They didn’t explode on his face, they properly popped! It was a success and everybody at the office was offered to taste the microwaved-cooked popcorn.

Percy Spencer had effectively created the microwave oven and patented it. Now, people could use a box sending radio waves at a frequency of approximately 2,500 MHz into their food—the microwaves absorbed by the water, the fats, and the sugars in the food being converted to heat—to quickly cook or reheat their dinner.

Was it dangerous? No, of course! Well, nobody knew, even Spencer. But nobody cared for that type of thing at that time. Nevertheless, tests were conducted in 1968 at the Walter Reed Hospital, and the results confirmed it was not that safe, but the “leaks” were fixed by 1971.

The First Commercial Microwave Oven

On October 8, 1945, Raytheon filed a patent for Spencer’s “Method of treating foodstuffs,” but it wasn’t until 1947 that the corporation produced the first commercial microwave oven. Due to its origins, I suppose, they called it the “Radarange.”

The Radarange was a beast. It was almost 5 ft 11 in (1.8 meters) tall, weighed 750 lb (approximately 340 kg), and consumed 3 kilowatts. The cost was also impressive: around U.S.$5,000 ($61,000 in 2021 dollars).

An 1970s ad for the Amana Radarange microwave oven
Amana Radarange Ads from the early 1970s.

It was not for everybody. In fact, it took years to produce microwave ovens that could be commercially viable. In 1967, a division of Raytheon called Amana introduced the countertop Radarange microwave oven, and this one could fit into the kitchen. It was still expensive and a bit large (and had a power of 1600 watts), but this 100-volt microwave oven cost just under $500.

Soon, other companies entered the market with new models, and, by 1976, the microwave oven reached nearly 60% of U.S. households. It became a more commonly owned kitchen appliance than the dishwasher.

As for Percy Spencer, he stayed at Raytheon and worked there until he died at the age of 76. In 1999, he was inducted into the National Inventors Hall of Fame.

You can read a bit more about microwave ovens on the SMECC website. If you are interested in reading about inventions that changed the way we eat, I also wrote about the creation of the toaster.

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