# How Percy Spencer Invented the Microwave Oven

> This 1945 patent describes the process of using concentrated microwave energy to cook food, the fundamental technology behind the modern microwave oven.

- **Patent:** US 2495429
- **Original title:** Method of treating foodstuffs
- **Owner:** Raytheon Manufacturing Co
- **Granted:** 1950
- **Status:** Public domain (expired)
- **Times cited:** 20
- **Field:** consumer_electronics, mechanical

## What it does

The patent outlines a method for cooking food by generating electromagnetic waves specifically in the microwave range. It requires guiding and concentrating these waves into a restricted, enclosed space where the food is placed. By exposing the food to this concentrated energy for a specific duration, the internal temperature of the food rises, effectively cooking it.

## What it does NOT cover

- Does not cover the specific electronic circuitry or magnetron design used to generate the waves.
- Does not cover methods of cooking that use infrared radiation or traditional convection heat.
- Does not cover the use of microwave energy for non-food applications like telecommunications or radar.

## The clever bit

The invention recognized that high-frequency electromagnetic waves could be trapped and directed to excite water molecules in food, causing rapid heating through dielectric loss rather than external heat transfer.

## Real-world examples

1. Amana Radarange
2. Modern household microwave ovens
3. Industrial microwave food processing equipment

## Why it matters

This patent is the origin of the microwave oven, a device that transformed domestic life and the food industry. It turned radar technology, developed for military use during World War II, into a common household appliance.

## Frequently asked questions

### What does How Percy Spencer Invented the Microwave Oven cover?

This 1945 patent describes the process of using concentrated microwave energy to cook food, the fundamental technology behind the modern microwave oven.

### Who owns patent US 2495429?

Raytheon Manufacturing Co owns this patent, granted in 1950.

### When does this patent expire?

This patent has expired and is now in the public domain — anyone can use the invention freely.

### What is patent US 2495429 cited by?

This patent has been cited by 20 later patents that build on its ideas.

### What problem does this patent solve?

This patent is the origin of the microwave oven, a device that transformed domestic life and the food industry. It turned radar technology, developed for military use during World War II, into a common household appliance.

### What does this patent NOT cover?

Does not cover the specific electronic circuitry or magnetron design used to generate the waves.

**Full plain-English explainer:** https://patentbrief.org/patent/us/2495429/microwave-oven-cooking

**Original patent:** https://patents.google.com/patent/US2495429

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_Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._


## Related patents

Semantically similar inventions in the PatentBrief corpus:

- [How Clarence Birdseye Invented Modern Frozen Food](https://patentbrief.org/patent/us/1773079/frozen-food-birdseye) — This 1930 patent describes the process of rapidly freezing food in small packages to prevent the formation of large ice crystals that ruin texture and flavor.
- [How the 1940 Nachumsohn Cooking Apparatus Works](https://patentbrief.org/patent/us/2187888/crock-pot-slow-cooker-naxon) — A 1940 patent for a cooking device designed to heat food efficiently using an enclosed chamber and specific heat distribution methods.
- [How Microwave Crisping Sleeves Work](https://patentbrief.org/patent/us/4267420/microwave-popcorn-susceptor) — General Mills' 1978 patent on using a thin, metal-coated plastic wrap that converts microwave energy into intense surface heat to crisp and brown food like Hot Pockets.
- [How John Harvey Kellogg Invented Flaked Breakfast Cereals](https://patentbrief.org/patent/us/558393/corn-flakes-kellogg) — A foundational 1896 patent describing the process of creating thin, toasted flakes from cooked grains, which launched the modern breakfast cereal industry.
- [How Cup Noodles Are Designed to Cook Perfectly](https://patentbrief.org/patent/us/3997676/cup-noodles-instant-ramen-ando) — A 1976 patent describing the specific shape, density, and placement of dehydrated noodles inside a cup to ensure they cook evenly and quickly when hot water is added.