Net Power

Net Power is defined as Forward Power minus the Reflected Power. This document describes the formula's that should be used to correctly calculate the Net Power.

Given information

Frequency [MHz]	Forward Power [dBm]	Reflected Power [dBm]
201,973	50	30

Question: What is the Net Power?

Answer: 49,95635195 dBm

The calculation

First you calculate the dBm values to linear values.

${\displaystyle 50\$dBm=10^{\frac {50}{10}}\ mW=100\ W}

${\displaystyle 30\$dBm=10^{\frac {30}{10}}\ mW=1\ W}

Subtract the linear values

$Net\ Power=Fw-Rf=100-1=99\ W$

Convert the value to dBm again:

${\displaystyle 10*log10(99*1000)\approx 49,95635195\$dBm}

Power expressed in milliWatt in dB values.

• 1 mW = 0 dBm

• 2 mW = 3 dBm

• 100 mW = 20 dBm

• 1 W = 30 dBm

• 100 W = 50 dBm