What is the calculated EIRP for AP1 given Ptx 16 dBm, antenna gain 8 dBi, and 4 dB cable loss?

What is the calculated EIRP for AP1 given Ptx 16 dBm, antenna gain 8 dBi, and 4 dB cable loss?

• A. -9 dBm
• B. 20 dBm
• C. 40 dBm
• D. 15 dBm

Answer: (B)

The calculation tests how EIRP combines transmitter power, antenna performance, and line losses. EIRP represents the power that would be radiated in a given direction if the antenna’s gain were replaced by an isotropic source, so you add the transmitter power and the antenna gain and then subtract any losses in the feedline. So you take the transmitter power of 16 dBm, add the antenna gain of 8 dBi, and subtract the 4 dB cable loss: 16 + 8 − 4 = 20 dBm. Therefore, the calculated EIRP is 20 dBm, which corresponds to 100 mW of power in that direction.

The calculation tests how EIRP combines transmitter power, antenna performance, and line losses. EIRP represents the power that would be radiated in a given direction if the antenna’s gain were replaced by an isotropic source, so you add the transmitter power and the antenna gain and then subtract any losses in the feedline.

So you take the transmitter power of 16 dBm, add the antenna gain of 8 dBi, and subtract the 4 dB cable loss: 16 + 8 − 4 = 20 dBm. Therefore, the calculated EIRP is 20 dBm, which corresponds to 100 mW of power in that direction.