Radiowave Reflection Homework | Calculate Voltage Vab

  • Thread starter leocfm
  • Start date
  • Tags
    Reflection
In summary, to calculate the voltage Vab at A due to current Ib in antenna B, we can use the principle of superposition and the formulas for single reflection to obtain a formula that takes into account multiple reflections and depends on the various parameters of the problem.
  • #1
leocfm
1
0

Homework Statement


As shown in the attachment, a radio signal travels down a tunnel, reflected by the walls and floor. Assuming that at most 2 hops contribute, calculate the voltage Vab at A due to current Ib in antenna B. Obtain a formula that depends on various parameters of the problem.

Homework Equations


Assuming antennas are polarization matched, the voltage Vab in receiver antenna A (effective length Ha) is given by Vab=Ha*Eb,
where Eb (the field at A due to source at B) and
Eb=((jωμIbHb)/4∏)*(exp(-jβd)/d) (where β is wavevector, d distance between A and B)

The Attempt at a Solution


What I have got is for single reflection, the field at A due to source at B is Eb=R*((jωμIaHa)/4∏)*(exp(-jβd)/d) where R is reflection coefficient of ground and d the reflected distance. But for multiple reflection, just like shown in the graph, how I can get the field at A?
 

Attachments

  • reflection.jpg
    reflection.jpg
    17.9 KB · Views: 420
Physics news on Phys.org
  • #2


To calculate the field at A due to multiple reflections, we can use the principle of superposition. This means that we can calculate the field at A by considering the contribution from each individual reflection separately and then adding them together.

Let's assume that the signal from B first reflects off the floor and then off the wall before reaching A. The field at A due to the reflection off the floor can be calculated using the formula Eb=Rf*((jωμIbHb)/4∏)*(exp(-jβdf)/df), where Rf is the reflection coefficient of the floor and df is the distance between B and the first reflection point on the floor.

Similarly, the field at A due to the reflection off the wall can be calculated using the formula Eb=Rw*((jωμIbHb)/4∏)*(exp(-jβdw)/dw), where Rw is the reflection coefficient of the wall and dw is the distance between the first reflection point on the wall and A.

Now, since we are considering at most 2 hops, the total field at A will be the sum of these two contributions, i.e. Eb = Eb(floor) + Eb(wall).

Plugging in the values for Rf, Rw, df, and dw, we can obtain the total field at A. This can then be used to calculate the voltage Vab using the formula Vab=Ha*Eb.

The final formula for Vab will depend on the various parameters of the problem, such as the reflection coefficients of the floor and wall, the distances between the antennas and the reflection points, and the effective lengths of the antennas.
 

1. What is radiowave reflection?

Radiowave reflection is the phenomenon of electromagnetic waves bouncing off of a surface, rather than being absorbed or transmitted through it. This can occur when the surface is not a good conductor of electricity, such as a metal plate or a building made of concrete.

2. How is voltage calculated in radiowave reflection?

Voltage in radiowave reflection is calculated using the formula Vab = Vao * (Rb - Ra) / (Ra + Rb), where Vab is the voltage at the point of reflection, Vao is the initial voltage, Ra is the resistance of the incident medium, and Rb is the resistance of the reflected medium.

3. What factors affect the amount of voltage in radiowave reflection?

The amount of voltage in radiowave reflection can be affected by the angle of incidence, the material properties of the surface, and the distance between the incident and reflected waves. Additionally, the frequency and wavelength of the radiowaves can also play a role in the amount of voltage produced.

4. How does the angle of incidence affect radiowave reflection?

The angle of incidence, or the angle at which the radiowaves hit the surface, can impact the amount of voltage in radiowave reflection. This is because a larger angle of incidence can result in a longer path for the reflected waves to travel, leading to a decrease in voltage. On the other hand, a smaller angle of incidence can result in a shorter path and potentially higher voltage.

5. What is the significance of calculating voltage in radiowave reflection?

Calculating voltage in radiowave reflection can provide important information about the behavior of electromagnetic waves and how they interact with different surfaces. This can be useful in fields such as telecommunications, where understanding how radiowaves reflect off of buildings and other structures can impact signal strength and quality.

Similar threads

  • Engineering and Comp Sci Homework Help
Replies
18
Views
1K
  • Introductory Physics Homework Help
Replies
9
Views
1K
  • Introductory Physics Homework Help
Replies
3
Views
2K
  • Engineering and Comp Sci Homework Help
Replies
10
Views
2K
  • Introductory Physics Homework Help
Replies
11
Views
1K
  • Introductory Physics Homework Help
Replies
3
Views
978
  • Engineering and Comp Sci Homework Help
Replies
1
Views
1K
  • Engineering and Comp Sci Homework Help
Replies
1
Views
2K
  • Engineering and Comp Sci Homework Help
Replies
1
Views
2K
Back
Top