The first microwave oven looked nothing like the compact box sitting on your kitchen counter. Built by Raytheon in 1947 and branded the “Radarange,” it stood nearly 6 feet tall, weighed 750 pounds, and resembled an industrial refrigerator more than a cooking appliance. It required its own water cooling system and a dedicated plumbing hookup just to operate.
How the Microwave Was Discovered by Accident
The microwave oven exists because of a melted chocolate bar. Percy Spencer, an engineer at Raytheon, was working in a laboratory near a magnetron, a vacuum tube that generates microwaves for radar systems. He noticed the candy bar in his pocket had begun to melt. Curious, he held a bag of unpopped popcorn next to the magnetron and watched the kernels burst into popcorn.
Spencer and Raytheon quickly saw the cooking potential and filed a patent on October 8, 1945. A working prototype was installed in a Boston restaurant for testing, and the commercial Radarange hit the market in 1947.
Size and Shape of the 1947 Radarange
The original Radarange was 5 feet 11 inches tall and weighed about 750 pounds. It was a freestanding metal cabinet, roughly the size of a large vending machine, with the cooking cavity set into the upper portion and the heavy electrical and cooling components housed below. The magnetron inside generated enormous heat, so the unit needed a water cooling line plumbed directly into it. You couldn’t just plug it into a wall outlet and start cooking.
The exterior was plain industrial steel, built for durability rather than style. This was a piece of commercial kitchen equipment, not a home appliance, and it looked the part. Think of the hulking metal cabinetry you’d see in a 1940s factory or hospital kitchen.
Controls on the First Models
The interface was strikingly simple. Early Radarange units had just two buttons: a green START button and a blue LIGHT button. Cooking time was set using two mechanical dials, one for 5 minutes and one for 25 minutes. The timers were additive, so you could combine them for up to 30 minutes total. In an unusual design quirk, the 5-minute dial sat on the bottom and the 25-minute dial on top, the opposite of what later models would do. The markings on the dials ran in the reverse direction of standard timers, and each dial only spun one way, with a ratchet mechanism on the 25-minute unit to prevent it from being turned backward.
Who Actually Bought One
At roughly $5,000 in 1947 dollars (equivalent to around $52,000 to $64,000 today, depending on the estimate), the Radarange was far too expensive for home kitchens. Raytheon marketed it exclusively to commercial buyers. Restaurants, industrial kitchens, and food processing operations were the primary customers, and even then, sales were limited. Some businesses used the machines for tasks that had nothing to do with cooking meals: drying potato chips, roasting coffee beans, and heating peanuts.
From Industrial Cabinet to Kitchen Counter
It took two full decades for the microwave to shrink down to something a household could use. In 1967, Raytheon’s subsidiary Amana introduced the first compact microwave designed for home kitchens. It measured about 15 inches tall, 23 inches wide, and 17 inches deep, roughly the footprint of a modern microwave. That’s a dramatic transformation from a 750-pound, nearly 6-foot-tall water-cooled machine to a countertop appliance that could sit next to your toaster.
The price dropped accordingly, though early home models were still a significant purchase. The real explosion in adoption came through the 1970s and 1980s as manufacturing costs fell and families discovered the convenience of reheating leftovers in minutes. By then, the microwave looked almost exactly like it does today: a rectangular box with a glass door, a turntable inside, and a simple control panel on the right side.