Question
How much power is being absorbed by the load when a directional power meter connected between a transmitter and a terminating load reads 100 watts forward power and 25 watts reflected power?
Answer Options
- A) 100 watts
- B) 125 watts
- C) 112.5 watts
- D) 75 watts
Correct Answer: D
Explanation
A directional power meter measures two distinct quantities: the power traveling from the transmitter towards the antenna (forward power) and the power reflected back from the antenna towards the transmitter (reflected power). The true power dissipated by the load (the antenna system) is the net power actually accepted by the load, which is the difference between these two measurements.
To find the power absorbed by the load, you must subtract the reflected power from the forward power. In this scenario, the absorbed power is 100 W - 25 W = 75 watts. This net power is the only energy that leaves the transmission line and is successfully radiated or dissipated as heat in the load itself.
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