In the figure shown below, what is the expected power level at the input to the receiver?

Concept:

Expected power level = Input power – Losses + Total Gain

Note: In dB, the gains are simply added.

To convert dBm to dBW and vice-versa:

P(dBm) = P(dBW) + 30

Calculation:

Given:

Input Power = -10 dBm

- 10 = P + 30

Input power = -40 dBW

Net losses = – 2 – 3 – 5 = –10 dBW

Net Gain = 20 + 30 = 50 dBW

Expected power level  will be:

= –40 – (2) + 30 – (3) + 20 – 5 = 0 dBW

P(dBm) = 0 + 30 

∴ 30 dBm will be the correct answer.