Received Power Calculator

Friis Transmission Equation:

\[ P_r = P_t \times G_t \times G_r \times \left( \frac{\lambda}{4 \pi d} \right)^2 \]

Transmitted Power (P_t):

Transmit Gain (G_t):

Receive Gain (G_r):

Wavelength (λ):

Distance (d):

Received Power (P_r):

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1. What is the Friis Transmission Equation?

The Friis transmission equation is used to calculate the power received by an antenna from another antenna some distance away. It's fundamental in wireless communications and radar systems for predicting signal strength.

2. How Does the Calculator Work?

The calculator uses the Friis transmission equation:

\[ P_r = P_t \times G_t \times G_r \times \left( \frac{\lambda}{4 \pi d} \right)^2 \]

Where:

\( P_t \) — Transmitted power (W)
\( G_t \) — Transmit antenna gain (dB)
\( G_r \) — Receive antenna gain (dB)
\( \lambda \) — Wavelength (m)
\( d \) — Distance between antennas (m)

Explanation: The equation accounts for free-space path loss and antenna gains to determine the received power level.

3. Importance of Received Power Calculation

Details: Accurate received power calculation is crucial for designing wireless communication systems, determining link budgets, and ensuring reliable signal transmission over distances.

4. Using the Calculator

Tips: Enter transmitted power in watts, antenna gains in dB, wavelength in meters, and distance in meters. All values must be positive and non-zero.

5. Frequently Asked Questions (FAQ)

Q1: What is free-space path loss?
A: Free-space path loss is the attenuation of radio energy between two antennas due to the spreading of the wavefront in free space.

Q2: How do I convert between dB and linear gain?
A: Linear gain = 10^(dB/10). The calculator automatically converts dB gains to linear scale for the calculation.

Q3: What are typical values for antenna gains?
A: Isotropic antennas have 0 dB gain. Directional antennas typically range from 3-24 dB gain, depending on design and application.

Q4: Does this equation account for real-world factors?
A: The basic Friis equation assumes free-space conditions without obstacles, reflections, or atmospheric effects. Real-world applications may require additional factors.

Q5: How does wavelength relate to frequency?
A: Wavelength (λ) = speed of light (c) / frequency (f). For radio waves, c ≈ 3×10^8 m/s, so λ ≈ 300/f for f in MHz.