I just realized that my cup of hot cocoa isn’t hot any more so what do I do? Of course, I put it in the microwave and heat it up. That simple act I, like most of us today, take for granted, but it got me thinking. How did the microwave oven get invented? Believe it or not it’s history goes back to WWII. In a previous column article called “Doppler What?” published February 16, 2014 I explained how Radar was invented and then used by meteorologists to follow storms. As you might recall I explained RADAR (RAdio Detection And Ranging) was first developed during WWII as a tool to find the enemy at a distance.
I’m pretty sure you have never heard the name Percy Lebaron Spencer before. Neither had I, but he is the person credited with inventing the microwave oven. How did this grammar school drop-out end up inventing something that now in the modern-day world we can’t live without? The answer lies in Spencer’s background. According to Wikipedia his father died when he was an infant and his mother passed away when he was seven years old. His uncle and aunt took him in, but his uncle also died so he needed to help support his aunt and himself. That’s why he quit school and got a job from age 12 to 16 working sun-up to sun-down at a spool mill. Spencer heard that the local paper was planning to install electricity in its facilities, so he studied as much as he could about electricity and got a job at the paper mill installing the wiring in the plant. When he turned 18 he joined the U.S. Navy and studied all the books he could find to learn as much as he could about how radios worked.
Wikipedia quotes Spencer concerning his education “I got hold of a lot of textbooks and taught myself while I was standing watch at night.” He also was self-taught in trigonometry, calculus, chemistry, physics, and metallurgy in addition to other scientific disciplines. I don’t know about you, but learning these subjects in high school and college was tough enough with a teacher or professor. Teaching yourself takes an exceptional amount of dedication and brain-power.
He became one of the nation’s leading experts in radar tube design and while working for Raytheon was the chief of their power tube division. With his help Raytheon secured a contract to make combat radar equipment for M.I.T’s Radiation laboratory. What does all of this have to do with microwaves? It has to do with how the Radar equipment was made. Back then they generated the microwave radio signals that were the core mechanism of the Radar signal with magnetrons. A cavity magnetron, according to Wikipedia “is a high-powered vacuum tube that generates microwaves using the interaction of a stream of electrons with a magnetic field while moving past a series of open metal cavities (cavity resonators). Bunches of electrons passing by the openings to the cavities excite radio wave oscillations in the cavity, much as a guitar’s strings excite sound in its box.” Spencer was awarded the Distinguished Public Service Award by the U.S. Navy for his work.
We still haven’t connected his work on Radar equipment with the microwave oven invention. How did the connection get made? As fate would have it, Percy Spencer was standing in front of an active Radar set while building magnetrons and he noticed that the candy bar he had in his pocket had melted. Apparently he was not the first person to notice this type of occurrence, but he was the first to investigate what was happening and how it was happening.
And what do you think he decided to use to test the heating power of microwaves? It’s something people all over the world use today without giving it a thought. He popped the first microwave popcorn. Once he put an egg in a tea kettle with the magnetron placed right above it. This experiment was not as successful because the egg exploded right in the face of a co-worker observing the test. That’s when Spencer decided to enclose whatever was to be heated in a metal box and Voila! The microwave oven was born. Raytheon filed the patent for the microwave oven on October 8, 1945 eventually calling it the “radar range.” The first commercially produced microwave was 6 feet tall, weighed 750 pounds and cost between $2,000 and $3,000.
You might think, like I did, that Percy Spencer became a wealthy man for inventing such a wonderful product, but you’d be wrong. He was paid the standard fee of $2.00 by Ratheon for inventing it while working on company time in the company’s facilities, with company equipment, and with company employees.
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