Radio Theory

Cellular networks use communications methods based on basic radio frequency (RF) transmission principles. Radio signals are created when an alternating electrical current is applied to an antenna. The range of frequencies that can be classed as being of RF is termed the ‘radio spectrum’. Higher frequency (and shorter wavelength) signals above 30 MHz tend to travel in straight lines and are also able to travel through the ionosphere, which generally makes them suitable only for ‘line of sight’ (LOS) transmission, which means that the transmitter and receiver do need a clear view of each other in order to exchange signals. Radio signal strength measurements form the foundation of forensic radio surveying. The unit known as the decibel was designed to enable easier calculations of power gains and power losses in a system.