POWER in transmitters

Hi,
I was wondering what is the meaning of power in transmitters ?
I have seen a few FM transmitters and none of them talk about the impedance of the antenna ,so how can we calculate the power ?

thank you

In case of doubt, power means achievable radiated power. Power can be basically measured. In ETSI SRD regulations,
e.g. the radiated power has to determined by a calibrated receiver, you don't need to know the antenna impedance
in this case. But in practice, most transmitter modules are impedance matched for a 50 ohm load.

thank you ,does that mean the output impedance of the transmitter is 50 ohms so it is supposed to be connected to a 50 ohm antenna ?

Correct - the driving and load impedance should be the same to transfer maximum power.

If you mis-match them, some of the power is lost, either in the driver, or the cable feeding the load.

Brian.