The Basics of Microwave Technology

microwave

Microwave is a radio wave that transmits thermal energy to warm up food, beverages, and other materials without an external heat source. It is part of the electromagnetic spectrum and lies in the frequency range between 300 MHz and 30 GHz. The microwave oven is an example of a device that uses this radiation for cooking. Other devices that use this technology include radar systems used for weather tracking, car speed guns, and air traffic control and communication transmissions. Natural sources of microwaves include cosmic microwave background radiation (studied to help understand the Big Bang) and stars, including our Sun.

The fundamental technology behind microwave hasn’t changed much since its invention by Percy Spencer at the end of World War II, using radar technology developed during the war. The key development was the cavity magnetron, a new type of magnet that produces electromagnetic waves with a very short wavelength, known as microwaves.

As the microwaves pass through foods and beverages, they cause water molecules in them to vibrate. The resulting friction causes them to warm up. The faster the microwaves travel through a food or beverage, the more intense the vibration is and the faster the food heats up. Spherical foods warm up faster than irregularly shaped ones because they have a lower surface area to volume ratio and the microwaves don’t need to travel as far to reach all parts of them. Sugars also speed up microwave heating because they are polar, with a positive charge on one end and negative on the other.