DCAN 14: Siting and Design of Radio Telecommunication Equipment
Annex C - Factors Affecting Radio Signals
1. In a similar way to light, radio waves travel in straight lines and are affected by obstructions, which can alter the radio signal. The main factors that affect radio signals are:
Shadowing – Terrain or Buildings partially reducing signal.
Attenuation - Strength of signal is reduced when passing through a building.
Diffraction – a signal can bend around an object to a limited extent.
Reflection – this reduces signal strength but may also aid coverage.
Signal loss due to shadowing from terrain
Signal strength reduced by attentuation
Signal loss due to shadowing from buildings
Signals can 'bend' round obstructions to some extent (diffraction)
Signal strength reduced by reflection from walls and other objects
Reflection can be used to achieve radio coverage in urban areas
2. Radio waves will penetrate certain materials such as brick, stone and steel. The reduction on signal strength depends upon the density of the material. This must be considered when providing networks within buildings.
3. The location of the transmitter antennas is important as signals from one cell can interfere with signals from a cell nearby operating at the same frequency. The antenna will usually have to placed high up in order to avoid blind spots created by the layout of buildings or terrain.