Solve First Fresnel Zone Question & Understand Conclusion

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In summary, the question involves calculating the first Fresnel zone for two towers located 500m apart with a frequency of 800Mhz. The first Fresnel zone has a radius of 6.84m at the midway point and a radius of 5.48m at a distance of 100m from either the transmitter or receiver. This indicates that all objects between the two towers must be shorter than 3-4m in order for the signal to propagate effectively. The formula used to solve the problem is F_1=((d*sqrt(2))/f)*(√(h1+h2)), where d is the distance between the towers, f is the frequency, and h1 and h2 are the heights of
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bos1234
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Homework Statement


I've solved this question but I don't understand the conclusion the book says.

Question reads:
2 towers(transmitter and receiver), both of equal height(10m) and separated by a distance of 500m. f=800Mhz. Calculate first fresnel zone

First Fresnel zone has a radius of 6.84m at the midway point.

Then it further says that,
at a distance of 100m from either the transmitter or receiver, the first fresnel zone has a radius of 5.48m. Consequently,all objects between the txer and rxer must be shorter than 3-4m in order to have the approximate equivalent free-space propagaion over the 500m path at 800MHz.

Firstly, when they say that "at a distance of 100m from either the transmitter or receiver" does that mean the dist. between reciever and txer is 100m? If so I am getting 3.06 instead of 5.48m

Secondly, what's the point of finding this when the 2 towers are located 500m from each other>

relevant formula:
http://en.wikipedia.org/wiki/Fresnel_zone
F_n=...
 
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  • #2
Homework Equations The Attempt at a Solution I solved it using the formula, F_1=((d*sqrt(2))/f)*(√(h1+h2))where d=500m, f=800Mhz, h1=h2=10mF_1=6.84m. I don't understand the conclusion though.
 

FAQ: Solve First Fresnel Zone Question & Understand Conclusion

What is the First Fresnel Zone?

The First Fresnel Zone is a theoretical region of space surrounding a transmitting antenna that affects the propagation of radio waves. It is defined as an ellipsoid shape with the antenna at one focal point and the receiving point at the other. The size and shape of the First Fresnel Zone is determined by the frequency of the radio waves, the distance between the transmitting and receiving points, and any obstructions in the path.

How is the First Fresnel Zone calculated?

The First Fresnel Zone is calculated using the following formula: F1 = 17.3√(d1d2/f), where F1 is the radius of the First Fresnel Zone, d1 and d2 are the distances from the antenna to the two points, and f is the frequency of the radio waves in GHz. The resulting value is the radius of the ellipsoid shape that defines the First Fresnel Zone.

Why is it important to consider the First Fresnel Zone in radio wave propagation?

The First Fresnel Zone is important because it affects the quality of the radio wave signal between the transmitting and receiving points. If the First Fresnel Zone is obstructed, the signal can be weakened or distorted, resulting in poor transmission quality. By understanding the size and shape of the First Fresnel Zone, engineers can design more efficient and reliable radio communication systems.

How does the First Fresnel Zone impact the line-of-sight between two points?

The First Fresnel Zone is an important factor in determining the line-of-sight between two points. If the line-of-sight between the transmitting and receiving points passes through the First Fresnel Zone, it means that there are no obstructions that could affect the radio wave signal. However, if the line-of-sight is obstructed by the First Fresnel Zone, it may result in a weaker or distorted signal.

What are the conclusions that can be drawn from analyzing the First Fresnel Zone?

By analyzing the First Fresnel Zone, engineers can draw conclusions about the quality and reliability of radio wave propagation between two points. If the First Fresnel Zone is unobstructed, it can be expected that the radio wave signal will have good quality and reliability. However, if the First Fresnel Zone is obstructed, it may result in a weaker or distorted signal, potentially affecting the overall performance of the radio communication system.

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