Electromagnetic radio waves with a frequency of 3 THz or less are collectively called “radio waves”. Humans have been using radio waves for about 120 years, but radio waves have been around for a long time in the natural world.
Radio waves have different properties depending on the frequency. Some are readily reflected by the ionosphere in the Earth’s upper crust, and some are readily absorbed by rain and water vapour.
Radio waves are used not only for communication and transmission, but also for various purposes such as GPS, weather radar, microwave ovens, wireless IC card systems and medical fields, depending on the difference and characteristics of such properties.
A region where molecules and atoms are ionized in the upper atmosphere around Earth, which exists between an altitude of about 80 km and 500 km. It has the property of reflecting radio waves and can be used for long distance communication.
Radio waves wavelength
The wavelength ranges from 10 cm to 100 km.
Discovery of electromagnetic radio waves
For the first time in 1864, James Clerk Maxwell had shown theoretically and mathematically how electromagnetic radio waves could be transmitted from one place to another without wires. After that, in 1886-1889, a German scientist Heinrich Hertz proved the theory of radio that this theory is correct.
After this, in 1890 an Italian scientist Guglielmo Marconi started working on wireless telegraphy when he was only 16 years old. And in 1900 he showed it by sending a radio message for the first time.
Formation of Radio Waves
Radio waves are produced by alternating current at radio frequency. This current is passed through a special conductor called an antenna. Extremely long waves are not practical because such a long antenna is not possible. Radio waves are also produced by intergalactic processes, but they are created only in distant deep space.
Radio waves are made up of photons. Photons are also infrared, visual light, ultraviolet, X-ray, gamma ray etc. Photons move at the speed of light (vacuum, light) and therefore radio waves travel at the speed of light. About 300 million meters per second or about 186,000 miles per second.
Radio waves are a type of electromagnetic wave. Electromagnetic radio waves are generated as follows.
A high-frequency current flows through a conductor, and a magnetic field is generated around it at right angles. An electric field is induced in an electric field, which in turn induces a magnetic field, which is generated and propagated one after the other. Typically, the most efficient part of this conductor that transmits radio waves is called the antenna.
It is not that radio waves are not generated unless an antenna is used. As long as a high frequency signal flows through a conductor, the radio waves are irradiated, but the radiation efficiency is not good, so the radiation intensity is low. It is also called a leaked radio wave because it is a radio wave that is not normally intended to be radiated.
This leaked radio wave becomes a jamming radio wave (noise) for other electronic equipment, so it is necessary to reduce it as much as possible. If you bring the radio closer to home appliances (TVs, PCs, LED lamps, etc.), you may get noise, which means the radio waves are leaking.
There are regulations on these both internationally and domestically, so it is necessary to keep them below a level that meets the standards. In general, take a method like taking a solid ground or sealing it with metal so that the radio waves don’t leak out. In addition, a noise filter is used on AC power outlets to prevent it from flowing back through the power cord and spreading throughout the house.
[Electromagnetic Radio Waves | Radio Waves Wavelength]