Cellular Communications Explained

conditions such as rain and fog have little effect on the signals. However, as the frequency increases

the atmosphere has a much greater effect on the level of attenuation in the signal path, and

at certain frequencies the loss that is introduced has to be considered.

However, as the frequencies rise above about 3 GHz the loss can introduce an additional degree of

variation into the path. As may be expected, the loss is dependent upon the amoun t of rain and

also the size of the droplets. As a rough guide, very heavy rain may introduce an additional loss of

about 1 dB per kilometre at around 5 GHz, and more at higher frequencies. The loss occurs for

two reasons. The first is absorption by the rain droplets, with the level of actual attenuation