iakobos,
small correction......
The antenna itself is rarely resonant: the tuning circuit provides an impedance transformation such that the correct load is presented to the transmitter (usually 50 +j0). This may appear academic until you have to start working out how much power is radiated (or more usually, turned into heat!)
The argument as to whether or not the transmitter should match the load is a different one which has occupied technical journals in vituperative correspondance, and I won't raise that here!