Does Energy Decay Occur in Sealed Metal Boxes with Excited Resonant Modes?

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SUMMARY

The discussion centers on the excitation of resonant modes in a sealed metal box and the subsequent energy decay. It is established that incident electromagnetic radiation can penetrate the metal via the skin effect, allowing for mode excitation. A small dipole antenna placed at the anti-node of the desired mode can effectively excite these modes. Energy decay occurs exponentially due to resistive losses in the non-perfect conductor walls of the box.

PREREQUISITES
  • Understanding of electromagnetic radiation and skin effect
  • Knowledge of resonant modes in 3D metal cavities
  • Familiarity with dipole antennas and their placement
  • Concept of resistive losses in conductive materials
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  • Research the skin effect in various metal types and thicknesses
  • Learn about the mathematical modeling of resonant modes in cavities
  • Explore techniques for minimizing resistive losses in metal boxes
  • Investigate the design and optimization of dipole antennas for mode excitation
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apoptosa
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Hey there, I recently solved for the resonant modes in a 3d metal box.

Thats nice, but I was wondering about how to actually excite the modes (its a sealed metal box)
Supposing I actually excited these modes by shining incident em radiation such that a portion [of the incident wave] penetrates by skin effect (assuming the thickness of the metal allows for penetration without too much attenuation).

Will I subsequently have gradual decay of the energy stored in my box? I.e will my resonant mode 'leak' out by a similar process as they were originally excited with?

Thanks-Hopefully that was cogent.
 
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Are you asking how to excite a cavity in your simulations? Or in the real world?
If it is the latter the answer is that this can be done with a small antenna (a dipole of some sort) placed where the mode you want to excite has an anti-node.
The idea is usually (but not always) to make the antenna so small that losses due to the coupling can be neglected (although if you actually want to measure what is inside your box you have no choice but to "tap" some of its energy).
In the undercoupled case most of the losses will be due to the fact that the walls are made from a non-perfect conductor, i.e. just resistive losses.

And yes, the energy in the box will decay exponentially,
 

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