Radio waves don't travel the same distance in all directions. Walls, doors, elevator shafts, people, and other obstacles offer varying degrees of attenuation, which cause the Radio Frequency (RF) radiation pattern to be irregular and unpredictable. Attenuation is simply a reduction of signal strength during transmission. Attenuation is registered in decibels (dB), which is ten times the logarithm of the signal power at a particular input divided by the signal power at an output of a specified medium. For example, an office wall (i.e., medium) that changes the propagation of an RF signal from a power level of 200 milliwatts (the input) to 100 milliwatts (the output) represents 3 dB of attenuation.

 

The following provides some approximations of the attenuation values through common office construction at 2.4 GHz (802.11b/g):

Other factors that can effect the range of an RF signal at 2.4GHz include concrete fiberboard walls, aluminum siding, pipes and electrical wiring, microwave ovens, and cordless phones.