Skin Depth Q: Cellphone Rings in Cavity

AI Thread Summary
A cellphone placed in a closed aluminum cavity still received a call, raising questions about RF signal penetration. The discussion highlights that unless an airtight seal is achieved, the enclosure may not be fully closed. Cellphones are engineered to detect very weak signals, and aluminum-to-aluminum contact alone is insufficient for effective shielding. Proper EMI/EMC design requires additional methods like contact fingers and conducting gels to ensure signal isolation. The conversation concludes with a commitment to improve the sealing technique in future experiments.
Thierry12
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I placed a cellphone in 2 half-spheres that i closed afterwards to create a metal cavity (aliminium 1mm) and called it (with another cellphone). The phone rang even if it wasn't supposed to considering the skin effect (wavelenght were about 0,04m and i couldn't see any holes). Anyone has a clue why?
 
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RF can get through very small gaps.
When you said you 'closed them' unless you made an airtight seal (difficult without some fancy machining) you didn't really close them.
Cell phones are designed to pick up very-very weak signals.
 
When you're designing enclosures for EMI/EMC, particularly at those frequencies, aluminum touching aluminum doesn't count. You have to use things like contact fingers, solder, mechanical pressure, conducting gels, and so on.
This link will give you some considerations and examples
http://www.cotsjournalonline.com/home/article.php?id=100057
 
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Next time i will close them proplerly! ty
 
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