You can communicate through the ground using seismographs and some form of Morse code as a last resort. There is no way to completely block all wireless communication unless you can block sound. Maybe if your world was made out of sand but even then packed sand will transmit sound wirelessly. In retrospect a solar flare would destroy any electrical device capable of producing sound through matter. When we speak and using body language we are communicating wirelessly. A habitat that is that inhospitable humans would probably have to live underground or underwater.
