Electromagnetic radiation refers to the waves of electromagnetic field radiating through space. This radiation includes radio waves, microwaves, ultraviolet, infrared, X-rays and gamma rays.
A mobile phone has both transmitter and receiver sections. When the mobile phone is turned on, it emits radio waves that consist of radio frequency (RF) energy—a form of electromagnetic radiation moving at the speed of light. It works by transmitting radio wave signals to (and receiving these from) nearby base stations. (Base station is an essential part because it links the individual mobile phone with the rest of the network.)
When talking on a mobile phone, your voice is captured through its microphone and a radio signal is generated from the mobile’s circuitry. The radio signal is transmitted through its antenna, which radiates through space. This transmitted radio wave is picked up
by the antenna at the base station. Then the mobile phone and base station start communicating back and forth through radio waves transmitted from their respective antennae.
Every antenna, either on a mobile phone or tower, radiates electromagnetic waves. Radio waves are the strongest near the mobile phone antenna but get weaker and weaker as you move
away from the phone. Similarly, radio waves are the strongest at the base station antenna.
The radiated power level near a tower is high but reduces as you move away from it. Typically, a base station may have several antennae mounted on a tower. The tower or mast itself does not radiate any energy; it is radiated from antennae mounted on it.
The maximum power near the tower is shown in the figure on this page. The tower should be tall enough, as shown in the figure, to avoid high power radiation to nearby areas. The cellular or mobile network in a city may have a large number of base stations. The more the number of antennae, the more is the radiation power intensity in the nearby area.