Microwave Oven History

Girl Using Microwave Oven Old Picture

This microwave oven history lesson will give you some interesting facts about how the microwave oven came into being. Microwave ovens have been a feature of most of our kitchens since the early to mid 1990’s. Did you know however that the first microwave ovens were already commercially available way back in 1947? These early appliances known then as RadaRanges cost around $3000 US, weighed approximately 340kg and stood 1.6m tall!

So how did we get from this… The mighty RadaRange Early Microwave Oven…to this? Modern Microwave Oven


Accidental Discovery

Like so many other household gadgets, the original idea for the microwave oven wasn’t borne out a desire to reduce the burden of domestic chores.

The history of the microwave began in 1940 when  John Randall and Harry Boot invented the cavity magnetron tube at Birmingham University in England. The magnetron tube quickly became hugely important during World War II as it was used by the Allied forces of Europe and America to emit microwave radar signals  to detect distant, Nazi enemy aircraft and ships.

In 1945, the American engineer, Percy Spencer was carrying out maintenance work on a live radar set. Whilst working within close proximity to the radar equipment, he felt a tingling sensation throughout his body and noticed that a chocolate bar in his pocket had completely melted. After some investigation he determined that it was the microwaves being emitted by the magnetron tube in the radar set which had caused the chocolate to get warm enough to melt.

Percy Spencer experimented further by directing the magnetron tube at kernels of corn. Activating the gun resulted in just what he was hoping – the first microwave popcorn. Percy Spencer then went on to build a metal box with an opening on one side and the magnetron tube poking through into another side of it. He used this box to heat his lunches and a variety of other foods he was curious enough to try out. There’s  a story of an occasion where he heated a whole egg in the device which unfortunately resulted in the egg exploding in his colleague’s face. This incident led to the addition of a door to close the box and prevent any further such incidents.

In October 1945 Percy Spencer filed a patent (US 2495429 A) for a “Method of treating foodstuffs” which details the process of heating food using microwaves. In the patent description, Percy Spencer provides examples of where cooking an egg and a potato using his microwave device use a tiny fraction of the energy used with conventional cooking. You can download a scan of the original patent below.

Method of Treating Foodstuffs – Patent US2495429A

Early Microwave Ovens

The first microwave ovens in history were giants compared with the ones we use today. They were first sold in 1947 by Raytheon, an American defence firm. The RadaRange as the machine was known sold for $5000, which would actually be $51,000 US in today’s money. These monsters stood almost 6 feet tall, weighed over a third of a tonne and pumped out a massive 3000 Watts of power. Of course, these first models were not suitable for domestic use and were sold for use in restaurants, ship’s galleys and large canteens.

By 1967, Domestic kitchen counter-top versions of the microwave oven were eventually made available. Sold by the firm Amana, they were priced at US$495 ($3,408 in today’s dollars).

Today’s Microwave

A company called Litton who were popular in the restaurant business developed the short, wide shape of the microwave oven we are used to seeing today.  Sales really took of in USA and Japan from the ten’s of thousands in 1970 to the millions by 1975. By the late 1970’s, technology improvements and cheaper electronic parts meant that microwave ovens became more practical and affordable. In 1986, 1 in 4 US households owned a microwave oven. By 1997, The U.S. Bureau of Labor Statistics reported that a staggering 9 out of 10 American households owned a microwave oven.

Today most microwaves continue to follow the same short, wide box format popularised in the 70’s. You can however buy from a wide range of differing microwave oven types. There are different sizes, colours, capacities and power outputs. Some sit on the kitchen work-top, some are built in to kitchen units and some are hung over the stove. Many microwave ovens today are able to not only microwave food, but can grill, use convection heat and even steam food. Whatever microwave oven you have, don’t just use it for reheating last nights pizza – it can do so much more.  So, when you’ve finished eating a delicious plate of microwave slow cooked lamb, thank Percy Spencer and his melted chocolate bar for giving us the idea for the microwave oven all those years ago.


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