Penetration Loss
Penetration loss is the attenuation the signal undergoes while passing through a building element. Typically plasterboard and wood produce a few dB, a brick wall 5-15 dB, reinforced concrete more than 10-20 dB, and a metal sheet 20-30 dB and above. As frequency rises, the loss in the same material generally increases.
The loss arises from two mechanisms: absorption within the material and reflection at the surface. In conductive materials the second dominates; a metal sheet does not absorb the signal, it reflects it back.
- Reinforcement inside concrete increases the loss markedly; plain concrete and reinforced concrete are not the same.
- Coated low-emissivity glass gives far higher loss than ordinary glass because of the metal oxide layer.
- Layers accumulate: the losses of two walls one after another add up and consume the link budget quickly.
Because these numbers vary with material, thickness and angle of incidence, they should be taken as orders of magnitude, not exact values. The practical conclusion is this: if the remote control has to work between enclosed volumes, doing the calculation over free space range is misleading. Even if you account for only 10 dB of loss per wall, you will see that behind two walls a total of 20 dB brings you down to roughly a tenth of the theoretical range.
Context in which this term is used: Wireless remote control installation: pairing, relay, safety