Fresnel Zone Calculator — Wireless Link Clearance | RFCalcLab
Maintain clear line-of-sight for microwave links. Calculate the first Fresnel zone radius and required 60% clearance. Prevent signal fading and diffraction in long-range outdoor wireless installations.
How to Use the Fresnel Zone Calculator
Enter the total link distance and the frequency. The tool calculates the first Fresnel zone radius at the midpoint, which is the most critical area for signal clearance.
If there is a specific obstacle, enter its distance from the transmitter (d1) to find the exact radius at that point. Obstacles within this zone will cause diffraction and signal loss.
Best practice is to maintain at least 60% clearance of the first Fresnel zone (R1) to ensure 'free space' propagation conditions and minimize fading.
Related Topics
- Fresnel zone calculator
- RF clearance
- wireless link
- Fresnel radius
- line of sight
- microwave link planning
Frequently Asked Questions
- What is the Fresnel Zone?
- The Fresnel zone is a series of confocal prolate ellipsoidal regions of space between and around a transmitting antenna and a receiving antenna. The first zone must be clear for optimal signal propagation.
- What is the 60% rule for Fresnel zones?
- As long as 60% of the first Fresnel zone is clear of obstacles, the path loss will be nearly identical to free-space path loss. If more than 40% is blocked, significant signal fading will occur.
- Does Fresnel zone matter for indoor Wi-Fi?
- Yes, but due to the short distances and many reflections (multipath), it is much harder to calculate and clear. It is most critical for outdoor, long-distance point-to-point links where reflections are fewer.