Say I amt transmitting an RF signal from an antenna through a non-freespace medium (e.g. sand, water, cement) how can I go about calculating the absorption losses up to a certain depth level? I feel like this should be a fairly common and well-known equation, but I cannot seem to find it. Thanks all.
EDIT: For simplicity's sake I am assuming the wave is only traveling through a single medium, meaning reflection is not a concern.