Electromagnetic wave propagation when blocked by metal

In summary, the conversation discusses the impact of a piece of flat metal placed in front of an electromagnetic wave, specifically in the context of building a thermal chuck using peltier for measuring femto amps from a device. The participants also inquire about potential problems and discuss the absorbance and grounding of the metal plate. The conversation also touches on the possibility of capacitive noise and ways to eliminate it, but notes that it may depend on the specific setup and the type of noise generated by the peltier element.
  • #1
vincenttswong
8
0
Dear all,
I am a newbie in electromagnetic wave. Can you educate me, what will happen when an electromagnetic wave is blocked by a piece of flat metal placed in front of it?

My intention is to build a thermal chuck using peltier for to measure femto amps from my device.
I am worried if EMF created from peltier will affect my measurement.

Below is my stack(top-down):
Device under test -> Metal plate(for conductivity) -> ceramic ->metal plate(connect to ground) -> Peltier -> Heatsink

Please feel free to comment if there is any potential problems.

Look forward to hearing suggestion from you.

Thank you


Regards,
Vincent
 
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  • #2
If the frequency is not too high (below visible light should be fine) or too low (with a wavelength larger than the device), the metallic surface will absorb some small fraction and reflect most of the intensity.
 
  • #3
mfb,
Thank you for your prompt reply. Instead of PWM, I am using a steady current source. Therefore frequency is not high.
You did mention about absorbance of small fraction of EM wave by the metal plate. Will the absorbed EM by metal plate(connect to ground) be 'drained' to ground? Am I overdoing it by connecting this plate to a clean ground?

Look forward to hearing from you.

Thank you

Regards,
Vincent
 
  • #4
I don't see where you expect electromagnetic waves at all. Constant, direct current does not lead to the emission of electromagnetic waves.
 
  • #5
mfb,
Thanks for your prompt response. I was out of town last week and has got no internet access.
Last question I have here:
Will the sanwiched metal-dielectric-metal layer caused capacitive noise? If yes, is there any ways that I can eliminate them? Can I simply ground all metal plates to drain the charges?

Look forward to hearing from you.

Thank you


Regards,
Vincent
 
  • #6
I think that will depend on details of the setup. Grounding metal plates makes them immune to low frequencies, but you can still have some HF-noise.
I don't know which kind of noise your peltier element generates.
 

1. What happens when an electromagnetic wave encounters a metal object?

When an electromagnetic wave encounters a metal object, it is either reflected, absorbed, or transmitted. The specific outcome depends on the properties of the metal and the wavelength of the electromagnetic wave.

2. Why does metal block electromagnetic waves?

Metal blocks electromagnetic waves because of its high electrical conductivity. This means that when an electromagnetic wave encounters a metal object, the electrons in the metal are able to move freely and absorb the energy of the wave, preventing it from passing through.

3. Can all types of metals block electromagnetic waves?

No, not all types of metals are equally effective at blocking electromagnetic waves. The ability to block electromagnetic waves depends on the electrical conductivity and thickness of the metal. Generally, thicker and more conductive metals are better at blocking electromagnetic waves.

4. How does the thickness of a metal object affect its ability to block electromagnetic waves?

The thicker the metal object, the more difficult it is for an electromagnetic wave to pass through. This is because there is a greater amount of material for the wave to travel through and be absorbed by. However, if the metal is too thin, it may not be able to effectively block the wave.

5. Are there any ways to prevent electromagnetic waves from being blocked by metal?

One way to prevent electromagnetic waves from being blocked by metal is to use materials that are less conductive, such as plastics or ceramics. Additionally, using specific designs or shapes can help redirect or scatter the electromagnetic waves, rather than allowing them to be absorbed by the metal.

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