Where does radiated power come from?
When you look at the input impedance of an antenna, there will be a real component, indicating that electrical power is delivered to the antenna. 

Part of the real component is due to resistive loss (electrical power transformed to heat), and part is due to radiated loss (electrical power transformed into radiated em waves).

Antennas are inherently not lumped circuit elements, so you can't use all the analysis techniques of lumped circuit theory when analyzing them.