Received Power Calculator (Pr) – Friis Transmission Equation for RF Links
Calculate received power (Pr) using the Friis transmission equation for accurate wireless link analysis.
IntermediatePower & Link Budget
About This Calculator
The Received Power (Pr) Calculator helps you estimate the power received by an antenna in a wireless link using the Friis transmission equation. It is an essential tool for RF engineers, telecom professionals, students, and wireless network designers who need to calculate signal strength in free-space conditions.
By entering transmit power, antenna gains, frequency, and distance, the calculator returns the received power in dBm or Watts. This makes it easier to evaluate link quality, coverage, and feasibility before deployment.
The formula assumes:
- clear line-of-sight propagation,
- far-field conditions,
- matched polarization,
- and no obstacles, reflections, or atmospheric losses.
This calculator is especially useful for WiFi networks, cellular systems, satellite links, IoT deployments, microwave backhaul, and drone communication systems. It also supports early-stage link budget planning, helping users determine whether a signal will remain above the receiver sensitivity threshold.
Received Power Formula Explained
The received power (Pr) is calculated using the Friis Transmission Equation, which describes how signal strength decreases over distance in free space.
Standard Formula:
Pr = Pt × Gt × Gr × (λ / 4πd)²
In dB form (most commonly used):
Pr (dBm) = Pt (dBm) + Gt (dBi) + Gr (dBi) − FSPL (dB)
Where:
- Pr = Received power
- Pt = Transmit power
- Gt = Transmitter antenna gain
- Gr = Receiver antenna gain
- d = Distance between antennas
- λ = Wavelength (c / f)
- FSPL = Free Space Path Loss
This formula shows that received power decreases as distance increases and improves with higher antenna gains.
Why Use This Calculator?
Received power is one of the most important values in RF design because it directly affects:
- signal quality,
- coverage range,
- data reliability,
- and link margin.
A strong received power value does not always guarantee a good connection, but a weak value usually means poor performance. That is why the Pr calculator is often used together with an FSPL calculator, link budget calculator, and antenna gain calculator.
Assumptions and Limitations
This calculator is based on ideal free-space conditions and should not be used alone for complex environments. Real-world networks may require additional losses for:
- fading,
- obstruction,
- polarization mismatch,
- cable loss,
- rain attenuation,
- and multipath interference.
Related Calculators
- FSPL Calculator
- Link Budget Calculator
- EIRP Calculator
- Antenna Gain Calculator
- Wavelength Calculator
- VSWR Calculator
Related Formulas
Pr = Pt × Gt × Gr × (λ / 4πd)² Pr (dBm) = Pt (dBm) + Gt (dBi) + Gr (dBi) + 20 log10(λ / 4πd) FSPL (dB) = 32.44 + 20 log10(d km) + 20 log10(f MHz) Pr (dBm) = Pt (dBm) + Gt (dBi) + Gr (dBi) - FSPL (dB)
Common Use Cases
Wireless link budget analysis WiFi range estimation Cellular network planning Satellite communication design IoT and LoRaWAN network analysis Drone-to-ground RF link planning