When you hear the term radio wave, you automatically think of broadcasting, mobile communications, and navigation systems. This is a limited perception referring to the lot of artificially-produced radio waves. Naturally-occurring radio waves, on the other hand, are produced by astronomical objects and lightning.

A radio wave actually pertains to a type of electromagnetic radiation. Like other types of waves in the electromagnetic spectrum, a radio wave is produced by acceleration of an electric charge and has both electric as well as magnetic components.

Waves of the electromagnetic spectrum are arranged either according to frequency or wavelength. The higher the frequency of the wave, the shorter is the wavelength and vice versa. In the waves of the electromagnetic spectrum ordered based on decreasing frequency, gamma rays come first, followed by x-rays, ultraviolet radiation, then visible light, infrared, and finally microwave and radio wave. This means that radio waves have the lowest frequency but the longest wavelength.

The existence of radio wave was discovered through the mathematical work of James Clerk Maxwell and demonstrated by Heinrich Hertz. What makes radio waves and other waves of the electromagnetic spectrum interesting is that they are able to travel even without the existence of a medium for transmission. They are, thus, able to travel from interplanetary or interstellar space toward the Earth.

The discovery of radio wave has brought about the existence of useful applications for man including in the fields of communication and medicine. For instance, radio frequency energy has long been used in less invasive medical procedures.