RF Budget Calculator: RSSI and Free Space Path Loss

This page provides an RF Budget calculator, also functioning as an RSSI (Received Signal Strength Indication) calculator. The power at the receiving antenna can be considered as RSSI. RSSI measures the power of the received RF signal.

It can be measured directly at the RF level or at the baseband level using I/Q samples.

EXAMPLE:

• INPUTS:

  • Frequency (GHz) = 4
  • Distance (meters) = 35863E03
  • Transmitter gain (dB) = 48
  • Receiver Gain (DB) = 44
  • Transmitter Power (dBW) = 24

• OUTPUTS:

  • Free Space Path Loss (dB) = 195.57
  • Power received (dBW) = -79.57

RF Link Budget Equation

The term “RF budget” is commonly used in the satellite communication field. When an RF signal travels from one end to the other, it experiences attenuation. The amount of attenuation depends on the medium through which the electromagnetic wave is traveling.

In satellite communication, the primary loss occurs in free space. This free space loss depends on the distance between the transmitter and receiver, as well as the wavelength (or frequency) of operation.

Free space path loss = (4*π*d/λ)^2

The following equation (or formula) is used for the RF budget calculator. This calculator determines the power received at the satellite receiver and the free space path loss. Transmitter power and antenna gains are input to the RF budget calculator.

This RF budget calculator calculates power received at satellite receiver and free space path loss. Transmitter power and antenna gains are provided as input to the RF budget calculator.