Skin Depth Q: Cellphone Rings in Cavity

[Thierry12]

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 (wavelength were about 0,04m and i couldn't see any holes). Anyone has a clue why?

 

[mgb_phys]

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.

 

[TVP45]

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

 

[Thierry12]

Next time i will close them proplerly! ty