In low freq magnetic communication, the carrier is not EM wave but low frequency varying magnetic field. Most of the energy is transmitted within the mag field, very little result in EM wave. I find this very strange, because in Maxwell equation's plane wave solution, B is always equal to E/c. According to the link this site don't allow me to post(@$&^&*%), they do it by having the antenna a lot smaller than wavelength. My question then is when is E = B/c valid? When not?