dBW and dBm
Remember that Gain relates to a ratio of
Power Out -to- Power In
whether Gain is expressed as a simple ratio or expressed in dB's.
So knowing the Gain of a system does NOT tell you the Power Out,
i.e. Gain does not represent absolute power
Of course by selecting some standard reference power, like 1 watt, an absolute power could be represented by using the same LOG form that is used to define the dB.
10 x LOG(P / 1watt)
as though talking about a system where PIN is 1 watt.
