Microwave Ovens

The microwave oven emerged from radar experimentation during World War II. Percy Spencer, an employee of the Raytheon Corporation of Waltham, Massachusetts, walked in front of a magnetron that was emitting microwaves and discovered that microwaves had heating properties. After the war Spencer patented the process of heating food by conveying it under two parallel magnetrons. Two years later William M. Hall and Fritz A. Gross, who were coworkers of Spencer’s, patented a microwave heating device enclosed in an oven. The prototype microwave oven constructed by Spencer in 1946 cost approximately $100,000. In 1947 Raytheon began constructing commercial ovens, calling them Radaranges. The main use of these ovens was heating cold sandwiches and other foods. Because these early microwave ovens cost in excess of $3,000, sales were mainly limited to restaurants, railroads, cruise ships, and vending-machine companies.