When were microwaves invented?

By George Garza
Info Guru,

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Popcorn in bowl
Microwave popcorn wouldn't exist if it hadn't been for an accidental discovery
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How was the microwave created?

The prevalent home technology after World War II was the television, the stereo system and radio, the conventional oven, the washer and dryer, the refrigerator, and the microwave oven. When were microwaves invented? The microwave oven was developed from the military experience. It was a byproduct of radar technology.


Radar was invented early in World War II. Radar was an early airplane detection device. Primitive by today's standards, it nevertheless was instrumental in the defense of Britain in the early years of the war. A part of the radar technology was a device called a magnetron. This was an important part of the microwave frequency generating device that radars used to find planes in the distance.

Effects of Radar

One unusual effect of radar that was not anticipated was that birds getting too close to the transmitter were cooked. They weren't sure what the cause was; they could not easily investigate because it was so expensive to create the electronics, and because the electronics were so large. But as transistors took over the industry, the technology became small enough that they were affordable. It was now possible to study it.

The Electro-Magnetic Spectrum

Microwaves are part of the electro-magnetic spectrum. The spectrum has been around since right after the Big Bang. But as with most scientific discoveries, the public's scientific interested waned in comparison to the commercial application that had yet to be introduced. So when were microwaves invented?

Discovery of Microwave Applications

As we have mentioned, radar operators noted that birds that came close to radar transmitters were cooked. But they could not find out why until after World War II.

It all began in 1946 at the Raytheon Corporation.  Dr. Perry Spencer was a self-taught electronics engineer. While touring one of his labs, he stopped in front of the magnetron the power tube that was responsible for radar.  He had a candy bar in his shirt pocket. To his surprise, the candy bar had melted.

As mentioned earlier, Spencer was not the first to notice this phenomenon but he could investigate it. As the holder of 120 patents, Spencer was no stranger to discovery and experiment he realized what was happening. The radar had melted his candy bar with microwaves. The first food to be deliberately cooked with microwaves was popcorn; the second was an egg, which exploded in the face of one of the experimenters.

The First Microwave Oven

The first patent was filed in 1945 by Spencer; in 1947, the first oven, the Radarange, was out. Early machines were not very efficient only about a third as efficient as today's microwaves. The first microwave was gigantic: it weighed 750 pounds and was five feet, six inches tall.  They were very expensive also. But development continued until the modern unit came out in the 1960s.  Prices dropped and made it a successful home appliance.

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