Actual height of Fresnel forbidden zone - distance between line and elipse

In summary: The values for λ, d1, and d2 can be determined from the given variables: ht, hr, Dtr, and D. In summary, the problem is to calculate the height h of the 1. Fresnel ellipsoid for various cases, using the formula r = (λ*d1*d2)/(d1 + d2) and known values for ht, hr, Dtr, and D.
  • #1
tblues87
1
0
Hi
I'm new here so I don't know if I posted in right place but here is the problem.

I don't know if you are familiar with antenna theory but I need to calculate radius of 1. Fresnel ellipsoid. It's easy when two antennas are on same altitude but if they aren't there is a problem.

If you look the picture in attachment you will see that I need to calculate height h.
I won't give you and numbers because I need calculation for various cases but here are known variables:

ht - height of first antenna
hr - height of second antenna
Dtr - distance between antennas
D - distance between first antenna and point where h needs to be calculated
r - radius of 1. Fresnel ellipsoid on distance D

r=sqrt((λ*d1*d2)/(d1+d2))
λ=f/c

f - frequency
c - speed of light

These are all known numbers for various cases and for each of them I need to calculate h

Thank you very much.
 

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  • #2
Since the Fresnel ellipsoid is defined by the equation, r = (λ*d1*d2)/(d1 + d2)where λ is the wavelength of the signal, and d1 and d2 are the distances from the two antennas, you can use this equation to solve for h. Rewriting the equation to isolate h, we geth = (λ*d1*d2)/(d1 + d2) - Dtrwhere Dtr is the distance between the two antennas. Therefore, you can calculate h by plugging in the known values for λ, d1, d2, and Dtr.
 

1. What is the Fresnel forbidden zone?

The Fresnel forbidden zone refers to an area of space where certain types of waves, such as electromagnetic or sound waves, are unable to propagate due to interference from another object or surface. This can result in a decrease in signal strength or distortion of the wave.

2. How is the actual height of the Fresnel forbidden zone determined?

The actual height of the Fresnel forbidden zone is determined by calculating the distance between the line of sight and the ellipsoidal surface of the obstacle. This distance is influenced by factors such as the wavelength of the wave, the height and shape of the obstacle, and the angle of incidence of the wave.

3. What is the significance of the distance between the line and the ellipse in the Fresnel forbidden zone?

The distance between the line and the ellipse in the Fresnel forbidden zone is important because it determines the strength and clarity of the wave signal. If this distance is too small, the wave may experience interference and result in a weaker or distorted signal. Therefore, it is crucial to consider this distance when setting up communication systems or designing structures near wave transmission paths.

4. Can the actual height of the Fresnel forbidden zone be changed?

Yes, the actual height of the Fresnel forbidden zone can be changed by altering the factors that influence it, such as the height and shape of the obstacle or the angle of incidence of the wave. In some cases, physical barriers such as reflectors or diffusers can also be used to manipulate the wave and alter the size of the forbidden zone.

5. How does knowledge of the actual height of the Fresnel forbidden zone benefit scientists and engineers?

Understanding the actual height of the Fresnel forbidden zone is crucial for scientists and engineers in designing and optimizing communication systems and structures. By taking into account this distance, they can ensure that the wave signals remain strong and undistorted, allowing for efficient and reliable communication and operation of various technologies.

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