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A Brief Guide on Radio Waves

"Radio waves" transmit music, conversations, pictures and data invisibly through the air. It happens every day in so many different ways! Have you ever wondered what the Radio Waves are?

Radio waves are part of a larger group of waves classified all together as electromagnetic radiation. Radio waves have the longest wavelengths in the electromagnetic spectrum. Radio waves do more than just bring music to your radio. They also carry signals for your television and cellular phones.

Radio's long wavelength allows it to circumvent obstacles and travel long distances, unlike visible light and other spectra of higher frequencies. .Of the various kinds of electromagnetic waves, radio waves have a longer wave length than infrared rays, and are defined by the Radio Law as 'electromagnetic waves with a frequency of less than 3,000 GHz (3 THz)'. Frequency refers to how long the measured time is between the "crest" and "trough" of a wave arriving at the source. 

Radio waves themselves are not something that humans invented. They have existed since the moment when the universe came into being. The longest radio waves typically encountered by humans are generated using the entire Earth as an antenna. These waves have a wavelength similar to the diameter of Earth. Radio waves are radiated onto the surface of the earth from the sun and the other stars, and electromagnetic waves (radio waves) also arise from movement of the earth's crust and from lightening and so on. 

The qualities of radio waves are often compared to those of sound waves, but the definitive difference is that radio waves are transmitted even in the absence of matter (a medium). (For sound waves to be transmitted air is required.) In other words, radio waves can even be transmitted in a vacuum. In fact, radio waves are transmitted from communications satellites.

The shorter the wave length of radio waves becomes, the more they take on the qualities of light, and the greater their straightness becomes. In other words, their energy is concentrated in one direction, and they are said to have strong directivity. Furthermore, the higher the frequency, the more acute is the attenuation of the wave's energy. Therefore, the lowest frequencies are used for communication with submarines, due to their low energy (for stealth) and high penetrating power.

Radio waves with a wavelength of less than around 10 meters are absorbed by the atmosphere. Otherwise, they bounce back and forth between the ionosphere and the ground, making radio ideal for transmitting over the horizon. As of technology has developed, equipment that utilizes radio waves such as television, mobile phones and so on has been introduced, and now radio waves are present all around us.

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