RF Link Budget Calculation Or RF Receive Power calculation

RF Link Budget Calculation is the calculation of the receive RF power at the Receiver based on the transmitter RF power, RF cable losses, Tx Antenna Gain, Free Space Loss(FSL) Rx Cable Loss, Rx Antenna Gain

So the equation is

Receive Power (dBm)  = Tx Power (dBm)  - RF Cable Loss(dB) + Tx Antenna Gain(dB)  - Free Space Loss(dB) - Rx Cable Loss(dB) + Rx Antenna Gain (dB)

The calculation of the Free Space Loss

With Kilo Meter as the unit for distance
Free Space Loss(FSL) dB = 32.44 + ( 20 * Log(Frequency in MHz) ) + ( 20 * Log(Distance_In_KM) )

With Miles as the unit for distance
Free Space Loss(FSL) dB = 36.6 + ( 20 * Log(Frequency_In_MHz) ) + ( 20 * Log(Distance_In_Miles) )

Error Vector Magnitude (EVM) db to percentage calculation

For converting  Error Vector Magnitude (EVM) from db to %(percentage), we can use the below formula

EVM in % = 100 * (10^(EVM in dB/20))


Example:

EVM = -18 dB

EVM % = [100 * 10^(-18/20)] %
EVM % = [100 * 0.125892] %
EVM % = 12.589 %