What Are Microwaves?

microwaves

The microwave (a portion of the electromagnetic spectrum) is a kind of radiation that carries information in waves. It has short wavelengths and is different from lower-frequency radio waves because they don’t deflect or bounce off the ionosphere, but travel in straight lines instead. Microwaves are used in point-to-point communications, wireless communication systems, radar, microwave ovens, and medical thermography and cancer therapy.

The first modern microwave generators, vacuum-tube devices called the klystron and the magnetron, were developed during World War II for use in radar systems. After the war, engineers like Percy Spencer of Raytheon adapted the technology for commercial microwave ovens, which became widely available in 1975. In the US, they have since replaced gas ovens in many homes.

Microwaves are also used in industrial procedures to dry foods, such as potato chips and beans, and to sterilize equipment. They heat food without affecting its texture, and they can penetrate plastic foils and other nonmetallic containers to cook and melt materials inside. The radiation also passes through the human body, where it is absorbed by water molecules and can cause tissue damage.

Because microwaves can be focused into narrow beams, they are favored for long-distance communication. The waves carry voice, data and video signals between mobile phones, cell phone towers and satellites. They can also carry signals over long distances through the atmosphere, allowing them to be sent over the ocean. Microwaves can also transmit signals through thick fog and rain forests, which are a problem for other types of communication. They are also used in astronomical observations. Scientists serendipitously discovered cosmic microwave background radiation, which fills the entire universe and may be a clue to its origins.