Friday, September 2, 2022

History of the Microwave

Amber Lemus Christian Author
Blogger: Amber Lemus

Westinghouse demo for the
1933 World Fair unit.
Public Domain

Welcome back to our blog series on the History of Ordinary Things. Today we venture into the little-known history of the microwave oven. This appliance is a fairly recent invention, but it has revolutionized kitchens across the world.

Did you know that the invention of the microwave was actually an accident?

As technology developed in the 20's and 30's, the exploration of using radio waves to heat substances was just beginning. At the 1933 Chicago World's Fair, Westinghouse demonstrated a machine that cooked foods between two metal plates attached to a short-wave transmitter. The Westinghouse team had found that foods cooked in mere minutes with this method, compared to an hour in a regular oven.

As WWII raged, the development of short wavelength radar brought the invention of the cavity magnetron. This piece of equipment is what triggered the invention of the microwave oven as we know it today. A contract was awarded to Raytheon technologies here in the United States to mass produce this magnetron.

A man by the name of Percy Spencer was one of the leaders on the project for Raytheon in 1945. Percy was a self-taught engineer testing a new vacuum tube when he realized that a chocolate bar in his pocket was all melted from the heat. I love it that he was just carrying chocolate in his pocket at work. My kinda guy. Apparently, he wasn't the first person to notice this phenomenon, however he was the first one to investigate it. He set up another experiment with popcorn kernels and placed them near the magnetron. They popped into fluffy morsels. Next, he placed a tea kettle with an egg inside, placed the magnetron directly above it, and turned it on. As one of his co-workers stood over the kettle watching, the egg exploded in his face.

One of the original Radaranges
Installed 1961.
Acroterion, CC BY-SA 3.0
via Wikimedia Commons

Seeing these results, Percy went to work. He created a metal box and attached a high-density electromagnetic field generator to it. The magnetron emitted microwaves into the box, which kept the microwaves contained. After a few tweaks, Raytheon filed a patent on October 8, 1945 and called the invention the "Radarange". Percy was paid a gratuity of $2.00 for the patent, and never received any royalties for the invention. He did, however, go on to be the Vice President and Senior Board member at Raytheon.

The Radarange was placed in a restaurant in Boston for testing. This first commercial unit was almost 6 feet tall, weighed about 750 lbs, and cost $5,000, which would equate to around $61,000 in today's money.

Fun fact: almost immediately after the invention of the microwave, companies like Whirlpool began signing contracts so they could add matching ovens and microwaves to their product lines. Some companies even offered a combination microwave-ranges option up until sometime in the 1970's.

It was the Japanese company Sharp Corporation that introduced the turntable (that rotating plate on the inside) for more even cooking and heating.
Modern matching microwave and oven.
Photo by JOSBRA design Unsplash


In 1967, Amana a division of Raytheon introduced the first relatively affordable, and more reasonably sized microwave priced at $495, which would equate to around $4,000 today. It wasn't until the late 70's that we saw an explosion of low-cost countertop models, like the ones we know today.

As you can imagine, it took a while for the microwave to develop and catch on. In 1986, roughly 25% of U.S. households owned a microwave, but by 1994 it was over 90%.

As I was researching for this article, I was amazed at the life and mind of Percy Spencer, the inventor of the microwave. He deserves a post all to himself, so next month will be microwave part two!

Do you own a microwave? What do you typically use it for?


Two-time winner of the Christian Indie Award for historical fiction, Amber Lemus inspires hearts through enthralling tales She has a passion for travel, history, books and her Savior. This combination results in what her readers call "historical fiction at its finest".

She lives near the Ozarks in her "casita" with her prince charming. Between enjoying life as a boy mom, and spinning stories out of soap bubbles, Amber loves to connect with readers and hang out on Goodreads with other bookish peoples.

Amber is a proud member of the American Christian Fiction Writers Association. Visit her online at and download a FREE story by subscribing to her Newsletter!

1 comment:

  1. Thank you for your post today and for your contributions in general to the blog! I had no idea that the microwave was so old! We use ours almost daily for thawing, heating leftovers and cooking frozen veggies.