# Power loss through a medium

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.

• Search for "Skin effect" formulae for loss vs frequency, depth and conductivity. Also, you really need to know the conductivity of the medium in question.
– user16324
Oct 8, 2015 at 16:41
• FYI, depending on the frequency, you might have worry about scattering as well. Oct 8, 2015 at 16:42
• When a radio signal is traveling through free-space and it encounters a change in media, you also need to worry about reflection, not just absorption in the new media. Just something to be aware of. Also, when you say "cement," I am guessing you mean "concrete." If the concrete is reinforced with steel bar, as most structural concrete is, it will probably act as a very strong screen for the RF radiation (depending on details of wavelength, etc). Oct 8, 2015 at 16:42
• Googlle "RF absorption" and find a table which deals with your proposed frequency and medium. Then do the math. Oct 8, 2015 at 17:22
• The lower the frequency the better - you should be able to find an answer I made on this very subject somewhere lurking in EE. Here is one link: electronics.stackexchange.com/questions/174075/rf-communication/… Oct 8, 2015 at 17:58