I want to find power of the electromagnetic waves generated from a welding cable. I built my own coil antenna that is 6.5 inches in diameter (circular) with 50 turns and hooked up the ends to a digital oscilloscope to measure the voltage (the internal resistance is 1MΩ if it matters). I measured 11Vpp with T=2.75μS on the coil when it was placed directly on top of the welding cable. The coil is placed directly on top of the cable, so it receives approximately 180 degrees of the signal. I know that Emf = N*dPhi/dt (where N=# of turns) and that Phi = Area*B*cos(θ). I've found what I thought was the right math to find the Poynting vector, but I am getting vastly insane numbers such as 139W/m^2 which cannot be right. How do I calculate 1) The power of the welding cable as an antenna, and 2) The intensity of the wave?