Physics

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Fresnel Zone Calculator.

Calculate the radius of a selected Fresnel zone.

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Set your values

Results update as you type.

02 / ANSWER

Wavelength

Distance to first endpoint

Distance to second endpoint

Zone number

Zone radius

0.000000m

Results update automatically as you type.

Use Cases

RF Link Planning

Determine the required clearance for a wireless link to avoid signal degradation. By calculating the first Fresnel zone radius, you can ensure obstacles like trees or buildings do not intrude.

Example: For a 5 GHz link (wavelength 0.06 m) with endpoints 1000 m apart, find the radius at the midpoint.

Antenna Height Optimization

Calculate the Fresnel zone radius at a specific point to decide how high antennas must be mounted to achieve line-of-sight clearance over terrain or structures.

Example: If the distance to the first endpoint is 300 m and to the second is 700 m, compute the radius for zone n=1.

Frequently Asked Questions

What is a Fresnel zone and why is it important?: A Fresnel zone is an elliptical region between a transmitter and receiver where radio waves travel. The first zone (n=1) is most critical; if obstructed, signal loss occurs. This calculator finds the radius at any point along the path to help ensure clearance.
How do I use the Fresnel Zone Calculator?: Enter the wavelength (in meters), the distance to the first endpoint (in meters), the distance to the second endpoint (in meters), and the zone number (n). The calculator computes the radius of that zone at the point between the endpoints.
What units should I use for the inputs?: All distances (wavelength, distance to first endpoint, distance to second endpoint) must be in meters. The zone number is a positive integer (1, 2, 3, ...). The result is the radius in meters.

Tips & Common Mistakes

Tips

Ensure all distances are in meters; convert kilometers to meters by multiplying by 1000.
For most links, the first Fresnel zone (n=1) is the most important; higher zones have larger radii but less impact.
The maximum radius occurs at the midpoint between the endpoints, so check that point for clearance.
Use the calculator to compare different zone numbers to understand how much clearance is needed for various levels of signal integrity.

Common Mistakes to Avoid

Using kilometers instead of meters for distances, leading to incorrect radius values.
Entering the zone number as 0 or a negative number; zone numbers must be positive integers.
Assuming the radius is constant along the path; it varies, so calculate at the point of interest.

Last updated: August 13, 2026

Use Cases

RF Link Planning

Determine the required clearance for a wireless link to avoid signal degradation. By calculating the first Fresnel zone radius, you can ensure obstacles like trees or buildings do not intrude.

Example: For a 5 GHz link (wavelength 0.06 m) with endpoints 1000 m apart, find the radius at the midpoint.

Antenna Height Optimization

Calculate the Fresnel zone radius at a specific point to decide how high antennas must be mounted to achieve line-of-sight clearance over terrain or structures.

Example: If the distance to the first endpoint is 300 m and to the second is 700 m, compute the radius for zone n=1.

Frequently Asked Questions

What is a Fresnel zone and why is it important?

A Fresnel zone is an elliptical region between a transmitter and receiver where radio waves travel. The first zone (n=1) is most critical; if obstructed, signal loss occurs. This calculator finds the radius at any point along the path to help ensure clearance.

How do I use the Fresnel Zone Calculator?

Enter the wavelength (in meters), the distance to the first endpoint (in meters), the distance to the second endpoint (in meters), and the zone number (n). The calculator computes the radius of that zone at the point between the endpoints.

What units should I use for the inputs?

All distances (wavelength, distance to first endpoint, distance to second endpoint) must be in meters. The zone number is a positive integer (1, 2, 3, ...). The result is the radius in meters.

Tips & Common Mistakes

Tips

Ensure all distances are in meters; convert kilometers to meters by multiplying by 1000.
For most links, the first Fresnel zone (n=1) is the most important; higher zones have larger radii but less impact.
The maximum radius occurs at the midpoint between the endpoints, so check that point for clearance.
Use the calculator to compare different zone numbers to understand how much clearance is needed for various levels of signal integrity.

Common Mistakes to Avoid

Using kilometers instead of meters for distances, leading to incorrect radius values.
Entering the zone number as 0 or a negative number; zone numbers must be positive integers.
Assuming the radius is constant along the path; it varies, so calculate at the point of interest.

Use Cases

RF Link Planning

Determine the required clearance for a wireless link to avoid signal degradation. By calculating the first Fresnel zone radius, you can ensure obstacles like trees or buildings do not intrude.

Example: For a 5 GHz link (wavelength 0.06 m) with endpoints 1000 m apart, find the radius at the midpoint.

Antenna Height Optimization

Calculate the Fresnel zone radius at a specific point to decide how high antennas must be mounted to achieve line-of-sight clearance over terrain or structures.

Example: If the distance to the first endpoint is 300 m and to the second is 700 m, compute the radius for zone n=1.

Frequently Asked Questions

What is a Fresnel zone and why is it important?

How do I use the Fresnel Zone Calculator?

What units should I use for the inputs?

All distances (wavelength, distance to first endpoint, distance to second endpoint) must be in meters. The zone number is a positive integer (1, 2, 3, ...). The result is the radius in meters.

Tips & Common Mistakes

Tips

Ensure all distances are in meters; convert kilometers to meters by multiplying by 1000.
For most links, the first Fresnel zone (n=1) is the most important; higher zones have larger radii but less impact.
The maximum radius occurs at the midpoint between the endpoints, so check that point for clearance.
Use the calculator to compare different zone numbers to understand how much clearance is needed for various levels of signal integrity.

Common Mistakes to Avoid

Using kilometers instead of meters for distances, leading to incorrect radius values.
Entering the zone number as 0 or a negative number; zone numbers must be positive integers.
Assuming the radius is constant along the path; it varies, so calculate at the point of interest.