First of all we have to understand what is radio frequency so let us discuss about it. Radio frequency is a term that refers to alternating current (AC) having characteristics that, if the current is input to an antenna, an electromagnetic (EM) field is generated suitable for wireless broad casting and/or communications. These frequencies cover a large portion of the electromagnetic radiation spectrum, extending from nine kilohertz to thousands of giga hertz (GHz). When the current called RF is supplied to an antenna, it gives birth to an electromagnetic field which propagates through space. This field is often called an RF field; in less technical jargon it is a "radio wave."

The wavelength of RF field is inversely proportional to the frequency. In the atmosphere, if f is the frequency in megahertz and s is the wavelength in meters, then s = 300/f The frequency of an RF signal is inversely proportional to the wave length of the EM field to which it corresponds. At 9 kHz, the wavelength is approximately 33 kilometers (km) or 21 miles (mi). At the highest radio frequencies, the electromagnetic wavelengths measure approximately one millimeter (1 mm). As the frequency is further increased to that of the RF spectrum, EM energy takes the form of infrared rays (IR), visible rays, ultraviolet rays (UV), X rays, and gamma rays.

There are many types of wireless devices which make use of RF fields. Cellular telephone, cordless telephone, television and radio broadcast stations, two-way radio services and satellite communications systems all operate in the RF spectrum. Many wireless devices operate at visible-light frequencies or IR, which have electromagnetic wavelengths shorter than those of RF fields. Examples are remote-control boxes, most television-set, some cordless computer keyboards, a few wireless hi-fi stereo headsets and mice.

We can divide the RF spectrum into several ranges, or bands. With the one exception of the lowest-frequency segment, every band represents the increase of frequency which is corresponding to an order of magnitude (power of 10). Radio waves are one of those electromagnetic waves which travel within the spectrum of electromagnetic. Radio waves are generally termed in their frequency, which is nothing but the number of times the waves goes through a complete cycle per second; or we can defined it by their wavelength, which is find by the length (by meters) which is traveled from the one wave’s crest to the next wave crest.