The first discovery of microwaves’ usefulness for cooking took place in a laboratory in the 1940s. This has then started the revolution of the microwave applications. A researcher who was working on radar equipment noticed that a chocolate candy bar he was carrying in his pocket had melted and began to investigate. It was then discovered that if microwaves were partly contained in an enclosure, microwave resonators, could be used to heat food. The result was that the company he was working for, Raytheon, filed for a patent of the technology used in modern microwave ovens.
Electromagnetic energy is transmitted through space in waves. Just like waves in the ocean, they have certain characteristics. A characteristic used to classify different electromagnetic waves is their wavelength (simply the distance between wave crests or troughs). Visible light is a form of electromagnetic wave and is known as “visible” because the human eye has evolved to detect and identify it in the different colors of the rainbow. In the example of visible light, the wavelength is between 400 and 700 nanometers (one-billionth of a meter). Microwaves have a wavelength so small that scientists refer to their energies in electron volts (eV) instead of wavelengths.
Today, microwaves have found useful applications in a number of different areas. These include communications, radar technologies and medical applications.
Microwaves in Communications
Satellites are a good example of microwaves used in communication. Many different broadcast signals use microwaves to transmit to satellites so they can then be transmitted back to dishes in many locations. The small wavelengths of microwaves make these signals highly directional, allowing the use of smaller dish sizes to capture the signal.
Microwaves in Radar
If a signal is transmitted via microwave and strikes an object in its path, some of the signal will be reflected back toward the source. This principle allows for microwave radar applications. By measuring the time it takes for the signal to return, calculating the distance to the object is possible.
Microwaves in Medicine
Specific therapies are accomplished by directing microwaves as certain tissues to cause them to heat up. A technique called ablation uses this principle to remove unwanted masses of tissue. This can be very beneficial in cases where a patient is not a good candidate for surgery.
From melting chocolate bars to advanced medicine, microwaves are a useful tool in modern life. Thanks to science and engineering, they are put to good use every day.