Reflection of EM plane wave from a moving object

In summary, the reflected field is just the field fluctuations from the moving source of plane waves, which are just scaled down versions of the original field, so you would solve for them just like you would for any other reflected field.
  • #1
sunjin09
312
0
A plane wave normally incident onto a perfectly conductive surface moving in the normal direction with constant velocity comparable to the speed of light. How do I solve such problem? If I treat the conductor as static, and the source of plane wave as a moving source, do I only need to consider doppler effect, i.e., the wavelength or frequency of the plane wave is scaled, and the speed of light is unchanged?

In general, how to I solve a scattering problem with moving scatterers? Do I just treat them as time-dependent media and substitute into Maxwell's equations and figure out all the time-derivatives?
 
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  • #2
Make a Lorentz transformation to the rest system of the conducting surface or moving object. Do the scattering calculation to find the reflected fields. Then LT these fields back to the original system.
 
  • #3
Meir Achuz said:
Make a Lorentz transformation to the rest system of the conducting surface or moving object. Do the scattering calculation to find the reflected fields. Then LT these fields back to the original system.

Thank you for replying, since I don't know Lorentz transformation (or anything about relativity), let me elaborate what I have in mind:

Assuming I'm a person standing at the conducting surface measuring EM field fluctuations, if the source of the plane wave is moving toward me, I would observe an EM fluctuation at a frequency higher than the frequency of the wave observed in the original frame, but it is still a plane wave, that's all I as well as the conductor can tell, so I can solve for the reflected field just like what I normally do. Now I go back to the original frame, recalling the source of the reflected plane wave (surface currents) is moving toward me, all I can feel is a fluctuation at a higher frequency than the ALREADY INCREASED frequency when I did my calculation in the moving frame. Does this sound about right? The frequency increases two times as a result of the Doppler effect in both forward and backward propagation, and the amplitude is unchanged?
 

FAQ: Reflection of EM plane wave from a moving object

What is the Doppler effect and how does it relate to the reflection of an EM plane wave from a moving object?

The Doppler effect is the change in frequency or wavelength of a wave as it is observed by an observer moving relative to the source of the wave. In the case of the reflection of an EM plane wave from a moving object, the Doppler effect causes a shift in the frequency and wavelength of the reflected wave, depending on the relative velocity between the source and the observer.

How does the angle of incidence affect the reflection of an EM plane wave from a moving object?

The angle of incidence, or the angle at which the wave hits the object, affects the reflection of the wave by changing the direction and intensity of the reflected wave. As the angle of incidence increases, the reflected wave is shifted further away from the original path of the incident wave, resulting in a weaker reflection.

Can the speed of the moving object affect the reflection of an EM plane wave?

Yes, the speed of the moving object can affect the reflection of an EM plane wave. As the speed of the object increases, the Doppler effect becomes more pronounced, resulting in a larger shift in frequency and wavelength of the reflected wave. This can also affect the intensity and direction of the reflected wave.

Are there any factors other than the speed and angle of incidence that can influence the reflection of an EM plane wave from a moving object?

Yes, other factors such as the composition and shape of the object, as well as the properties of the medium through which the wave is traveling, can also have an impact on the reflection of the wave. For example, a smooth and reflective surface may result in a stronger reflection compared to a rough and absorbent surface.

How can the reflection of an EM plane wave from a moving object be used in practical applications?

The reflection of an EM plane wave from a moving object has many practical applications, including radar and sonar systems, where the reflected waves are used to detect and locate objects. It is also used in medical imaging techniques such as ultrasound, where the reflected waves are used to create images of internal body structures.

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