Yes, if it is electromagnetic. A form of mosquito-netting that would create a Faraday cage would be similarly effective depending on where the source(s) were.

Yes, if it is electromagnetic. A form of mosquito-netting that would create a Faraday cage would be similarly effective depending on where the source(s) were. What is perhaps even more interesting, eddy currents on the boundaries of the cave could be used to indicate that you were being broadcast at.