Fresnel Zone Calculation Tool

Fresnel Zone Radius Formula:

\[ radius = \sqrt{\frac{\lambda \times d1 \times d2}{d}} \]

Wavelength (λ):

meters

Distance from transmitter (d1):

meters

Distance from receiver (d2):

meters

Total distance (d = d1 + d2):

meters

Fresnel Zone Radius:

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Fresnel Zone?

The Fresnel zone is an elliptical area between two antennas (transmitter and receiver) that radio waves spread into after leaving the antenna. Clearance of this zone is important for optimal signal strength in wireless communications.

2. How Does the Calculator Work?

The calculator uses the Fresnel zone radius formula:

\[ radius = \sqrt{\frac{\lambda \times d1 \times d2}{d}} \]

Where:

\( \lambda \) — Wavelength of the signal (in meters)
\( d1 \) — Distance from transmitter to the point (in meters)
\( d2 \) — Distance from receiver to the point (in meters)
\( d \) — Total distance between antennas (d = d1 + d2, in meters)

Explanation: The formula calculates the radius of the first Fresnel zone at a specific point along the path between two antennas. For optimal signal, at least 60% of the first Fresnel zone should be clear of obstacles.

3. Importance of Fresnel Zone Calculation

Details: Calculating Fresnel zone is crucial for designing reliable wireless communication links, especially for microwave radio, Wi-Fi, and other line-of-sight systems. Obstructions in the Fresnel zone can cause signal attenuation and multipath interference.

4. Using the Calculator

Tips: Enter wavelength in meters (can be calculated as speed of light divided by frequency), distances d1 and d2 from the point of interest to each antenna, and total distance d. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the significance of the first Fresnel zone?
A: The first Fresnel zone contains the majority of the transmitted energy. Keeping it at least 60% clear ensures minimal signal loss.

Q2: How do I calculate wavelength from frequency?
A: Wavelength (λ) = speed of light (299,792,458 m/s) / frequency (Hz). For example, for 2.4 GHz Wi-Fi: λ ≈ 0.125 meters.

Q3: What happens if the Fresnel zone is obstructed?
A: Obstructions cause signal attenuation, multipath interference, and potential link instability or complete failure.

Q4: Is the Fresnel zone the same along the entire path?
A: No, it's largest at the midpoint between antennas and tapers toward each end.

Q5: How does this relate to antenna height?
A: Antennas must be high enough to maintain sufficient Fresnel zone clearance over terrain and obstacles.