300W is way too much for wireless power transmission. Even 1W is too much. I was trying to get power from a typical 13.56MHz RFID card reader, and the most I could get was roughly 50mW at the receiving end, that is using air coils.
If you use ferrite cores and short distance you might get better transmission, the magnetic coupling is the key. However the more coupling you have the closer you are to a transfomer and the further you are from wireless transmission.