The size of holes or gratings in a Faraday cage determines its opacity or transparency based on their relationship to the wavelength of electromagnetic radiation. Specifically, holes must be smaller than half the wavelength to effectively block radiation, as larger holes create surface impedance that reduces current flow necessary for reflection. The physics behind this involves the behavior of holes as short metallic waveguides, which can cut off wave propagation if below critical dimensions. Additionally, resonant slots can radiate by deflecting surface currents, further influencing the cage's effectiveness.
PREREQUISITESPhysicists, electrical engineers, and anyone involved in designing or analyzing electromagnetic shielding solutions.
It's probably best to be more precise about what you don't understand about what you've read.merlyn said:Yes. I didn't know how to phrase the question.
I thought I could get a more succinct and definitive answer here.
I just wanted the basic mechanism explained, or at least a reference.PeroK said:It's probably best to be more precise about what you don't understand about what you've read.
It needs to be somewhat smaller than half a wavelength diameter to block radiation. Not to do with diffraction.merlyn said:Could someone explain to be the reason why size of the hole or grating in the case of Faraday cage is what determines if the screen or grating is opaque or transparent? I'm pretty sure it has something to do with interference patterns in classical physics.
Thank you all in advanced.
Wonderful...Why? What are the physics?tech99 said:It needs to be somewhat smaller than half a wavelength diameter to block radiation. Not to do with diffraction.
Do you have any references which I can explore further?tech99 said:The hole behaves as a very short piece of metallic waveguide. If it is smaller than certain critical dimensions it is cut-off and will not support propagation of a wave.
Another way to look at is that large holes create surface impedance which reduces the flow of current in the surface, which is necessary for reflection.
And another way to look at it is that resonant slots will radiate as they deflect surface currents around them.
Could it be resonance? The effect doesn't have a peak; it's just a high pass function.tech99 said:resonant slots will radiate