350-401 Question #273: Real Exam Question with Answer & Explanation

Question

Using the EIRP formula, what parameter is subtracted to determine the EIRP value?

Options

• Atransmitter power
• Bantenna cable loss
• Cantenna gain
• Dsignal-to-noise ratio

Explanation

Antenna cable loss (B) is subtracted in the EIRP formula because cable loss represents power that is dissipated (lost as heat) between the transmitter and the antenna before the signal is ever radiated - this loss must be accounted for to determine the actual power being effectively transmitted. The full formula is: EIRP = Transmitter Power (dBm) - Cable Loss (dB) + Antenna Gain (dBi).

• A (Transmitter Power) is wrong because transmitter power is the starting value in the formula - it is what you begin with, not what you subtract.
• C (Antenna Gain) is wrong because antenna gain is added to the formula, as it amplifies the effective radiated power in a specific direction.
• D (Signal-to-Noise Ratio) is wrong because SNR is not part of the EIRP calculation at all - it measures interference, not radiated power.

Memory Tip: Think of the formula as a budget - you start with your transmitter power, lose money (subtract) through cable loss, then gain money (add) with antenna gain. The only thing subtracted is what you lose along the cable. 📡

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