>A lowfer loop that is 50 feet on a side, and is placed over a ground plane, >has a radiation resistance of 2.2 u ohms at 185 kHz. The formula I've always used gives a free-space Rr of 244 micro ohms, and over a ground plane it would be twice that. 2.2 microwatts of radiated power for a 50-foot square loop with a current of 1 amp seems just a bit pessimistic :-) Lyle, K0LR