Microwave frequency (MF) radiation applications

RF waves are used in different ways. Some are familiar to most people, others aren’t. The most familiar way RF waves are used is through what is in the name, namely radio communication and in its broader sense wireless communication. This can be through radio stations that broadcast music and news messages to listeners in fixed locations or who are listening to their car radios. In other ways it’s used in portable devices such as wireless and cellular telephones and walkie-talkies. It’s also used in satellite communications, microwave (MW) point-to-point systems and in tropospheric scatter radio. This latter one was mainly used in the 1950’s until the 70’s when it was outperformed by satellite communications. It makes use of signals that bounce off particles in the troposphere, which is basically the first layer of the atmosphere which contains most weather conditions, including clouds and the like. This was much more effective than microwave relay systems that use multiple stations that relay the signal on the ground because microwaves are limited because of line-of-sight. The periodically placed relay stations make up for the limitation of line-of-sight and make it possible to pass on the signal. Of course satellites eventually set the modern standard for the most advanced communications through Microwave radiation. Blocking out MF radiation is also possible. DMAS produces microwave absorbing materials that can dampen these electromagnetic waves so a MF noise free testing lab can be established.

Microwaves for visualization

Another application of microwave frequency radiation is to visualize situations. Radar is one of the first things that comes to mind. It can be used for detecting objects or to estimate distances between objects or areas. It can even estimate the angle or the speed of a detected object. Microwave radiation is used for this. Another related way for visualization lies outside the usual levels of microwave radiation but works through radio waves of different frequencies (10-200 kHz). This is for example used in technology for television that doesn’t use cable or internet. Some medical devices are also outfitted with electromagnetic technology. MRI (magnetic resonance imagery) is a form of medical diagnostics that helps to visualize tissues of organisms without damaging them.

Heating with MF radiation

Another medical example, this time for practical use instead of diagnostics, is diathermy. Diathermy is used for medical treatment in which a couple of techniques can be applied that make use of radio or microwave radiation. Tissues and blood vessels are heated with these electromagnetic waves to make very precise and clean cuts that limit the amount of bleeding for example. In non-medical situations dielectric heating can be used to heat materials to various degrees. This can be applied to seal, weld, emboss materials like resin or plastic, to cure, bake or heat a substance in general. It typically uses a frequency between 10 and 70 MHz. Induction heating or heat treatment makes use of frequencies between 50 Hz to 27 MHz. For other industrial applications plasma processing is used which operates on frequencies of 100 kHz to 1250 MHz. Microwave radiation can clean silicon wafers that are used in semiconductors. Etching materials or hardening a coating, synthesizing polymers or adding chemicals to metals all fall under this category. And the most well known application for heating with microwaves is of course the commercial microwave oven. Consumer applications typically use 2.45 GHz to heat food.