Definition
Attenuation in radio is the reduction of signal power as a wave travels from transmitter to receiver. It accumulates from several mechanisms: the natural spreading of energy over an expanding wavefront, absorption and reflection by obstacles, loss in feed cables and connectors, and weather effects such as rain or dense foliage. Because it is measured in decibels, attenuation is logarithmic, so equal lengths of path do not shed equal amounts of signal.
Free-space path loss
The dominant component on a clear line-of-sight link is free-space path loss, the weakening caused purely by the wave spreading out as it propagates. Power density falls with the square of distance, following an inverse-square law, and free-space loss also rises with frequency, so higher-band links lose more over the same distance. This single term usually swamps cable and connector losses in a well-built system.
Managing attenuation off-grid
For sovereign mesh operators, attenuation is the adversary every deployment fights. You counter it by keeping the path clear, shortening or upgrading feedlines, raising antennas, and adding antenna gain rather than simply cranking transmit power, which regional rules cap anyway. Understanding where loss comes from is what lets a few milliwatts of LoRa reach across a valley.
Attenuation is the central loss term in path planning. See Link Budget for how it is tallied, Fresnel Zone for obstruction loss, and dBm for the units of loss.
In Simple Terms
Attenuation in radio is the reduction of signal power as a wave travels from transmitter to receiver. It accumulates from several mechanisms: the natural spreading…