Fresnel Zone Calculator

The amazing Fresnel zone calculator allows you to calculate the radius length at any point in the Fresnel space. As a result, you can ensure that your antennas transmit strong signals. We'll go over all you need to learn about this topic in this article. We'll explain what a Fresnel zone is in simple terms and give you the formulas you'll need to compute Fresnel zones. We'll also go over why Fresnel zones are crucial and how to find out how high your antennas should be to avoid signal interference.

Fresnel Zone - Definition and Working

In between transmitter and receiver antennas in wireless communication, there is a 3D circular zone. The distance between both the antennas and the frequency of the wireless signal dictates this zone. It's known as the Fresnel Zone, and it looks like this:

The line of sight path is the longest axis of the ellipsoid in the Fresnel zone. It's vital to keep it clear when there are structures between the antennas because it can create a signal loss. Signal loss can be caused by barriers that do not cross the line of sight path. How is that feasible, though?

Waves are sent in different directions by wireless antennas. Some waves will arrive at the receiver directly, referred to as direct beams, while others will arrive via reflection with other surfaces, referred to as indirect beams.

Because indirect beams travel a longer distance than direct beams, their phase angle is displaced in comparison to the direct beam. Destructive interference occurs when the phase angle moves by one-half wavelength, causing the signals to cancel.

We must keep at least 60% of the first Fresnel zone clear of impediments to avoid the detrimental impacts of indirect beams. The suggested figure is 80%. The second and third Fresnel zones are also important, although not to the same extent as the first. You can use our excellent Fresnel Zone calculator to figure out the radius of the first zone and its 60% limit.

Fresnel Zone Formula

The radius of the n-th Fresnel zone is calculated as follows: rn = √(n * λ * d1 * d2 / (d1 + d2)),

Fresnel Zone Formula

Where: λ = wavelength of the antenna's wireless beam; and d1, d2, rn, as shown in the diagram below:

We must remember that an ellipsoid is the largest at its centre if we wish to acquire the longest Fresnel zone radius (rnmax). That is, when d1 = d2 = D / 2 is used, the above formula becomes:

rnmax = √(n * λ * D / 4)

First Fresnel Zones Formula

For example, if we want to calculate the radius at any position in the first Fresnel zone, we can apply the formula: r = √(λ * d1 * d2/ (d1 + d2))

The longest radius of the first Fresnel zone is: r1max = √(λ * D / 4)

Using the wavelength formula, we now have: r1max = √(c * D / (4 * f))

f = frequency of the wireless beam

Remember that wireless waves (which are electromagnetic waves) travel at the speed of light, therefore c = 300,000 km/s. In addition, if we set D and f in kilometres and GHz, respectively, we get:

r1max is equal to 17.32 * √(D / (4 * f) in metres.

This equation can also be written as:

In metres, r1max = 8.66 * √(D / f).

What is the Importance of the Fresnel Zone?

As previously stated, 60 % of the first Fresnel zone must remain clear of interference in order for the signal to reach the receiver antenna without significant difficulty. This is a current source of worry because buildings and other objects frequently obstruct antennas and hence violate the rule.

For example, Take wind turbines, which are unquestionably changing the way we generate energy. Such machines can be 80 metres tall; the antenna height should be 80 metres plus the radius of the first Fresnel zone to achieve 100 % interference-free operation.

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How can I find out the First Fresnel Zone?

Follow these procedures to calculate the radius of the first Fresnel zone:

  • Step 1: Calculate the D distance between the transmitter and reception antennas. Decide on a distance in kilometres.
  • Step 2: Choose the f frequency that you'll use for wireless communication. GigaHertz is a unit of measurement for the speed of light (GHz).
  • Step 3: Calculate D / f's square root.
  • Step 4: Finally, multiply the last operation's result by 8.66. The longest radius of the first Fresnel zone, stated in metres, is the outcome. 

FAQs on Fresnel Zone Calculator 

1. What does the first Fresnel zone entail?

The first Fresnel zone is defined as a set of imaginary rings surrounding the direct path's centerline, with the distance between the transmitting antenna and each ring plus the distance between the ring and the receiving antenna being one-half wavelength longer than the direct path between antennas.

2. What is the total number of Fresnel Zones?

There are an endless amount of Fresnel Zones that can be calculated, however, the 1st Fresnel Zone has the greatest impact on the Wireless Network's performance.

3. In 3D, what is Fresnel?

According to the camera or viewing angle, the fresnel factor changes the reflectiveness of a surface. The reflectiveness of a surface increases as it moves away from the camera. Similarly, the reflectiveness of a surface decreases as it faces the camera.

4. What happens when the Fresnel distance is exceeded?

Ray optics is utilised until and unless the Fresnel distance equals the slit width. When the Fresnel distance exceeds the slit width, wave optics is activated.