A transmitter has a power output of 100 watts. There is a loss of 1.30 dB in the transmission line, a loss of 0.2 dB through the antenna tuner, and a gain of 4.50 dBd in the antenna. The Effective Radiated Power (ERP) is:

First, calculate the total system gain or loss in decibels (dB). Add the antenna gain and subtract the losses from the transmission line and antenna tuner. The total change is +4.50 dB (gain) - 1.30 dB (line loss) - 0.2 dB (tuner loss), which equals exactly a net gain of +3.0 dB. Next, apply this net gain to the initial transmitter power output. In decibel mathematics, a +3 dB change corresponds to exactly doubling the power. Therefore, if the transmitter outputs 100 watts, a 3 dB overall system gain doubles the Effective Radiated Power (ERP) to 200 watts. Distractors like 400 watts or 800 watts are incorrect because they would require a +6 dB or +9 dB system gain, respectively.