Radio Propagation Effects
Attenuation is the drop in the signal power when transmitting from one point to another.
It can be caused by the transmission path length, obstructions in the signal path, and
multipath effects. The following figure shows some of the radio propagation effects that cause
attenuation. Any objects which obstruct the line of sight signal from the transmitter to the
receiver, can cause attenuation.
Description Typical Attenuation due to Shadowing
Heavily built-up urban center 20dB variation from street to street
Sub-urban area (fewer large buildings) 10dB greater signal power than built-up urban center
Open rural area 20dB greater signal power than sub-urban areas
Terrain irregularities and tree foliage 3-12dB signal power variation