+ Post New Thread
Results 1 to 4 of 4

9th September 2017, 04:09 #1
 Join Date
 May 2017
 Posts
 18
 Helped
 0 / 0
 Points
 244
 Level
 2
Question on faraday cage formula for hole size
Hi,
I would like to know when they say in this website (http://wiki.backyardbrains.com/Exper...e_Faraday_Cage)
One rule of thumb often used for Faraday cages to prevent transmission is that the holes need to be no larger than 1/10 of the wavelength of the signal
I would like to know what does it really mean out of these 4 choices?
a) we need a hole smaller that a square hole whose sides =1/10 of the wavelength to prevent propagation
b) we need a hole smaller than a rectangle hole which has one side = 1/10 of the wavelength to prevent propagation
c) we need a hole smaller than a square hole whose diameter = 1/10 of the wavelength to prevent propagation
d) we need a hole smaller than a circle hole whose diameter = 1/10 of the wavelength to prevent propagation
Thank you

Advertisement

11th September 2017, 08:07 #2
 Join Date
 Feb 2017
 Posts
 73
 Helped
 9 / 9
 Points
 812
 Level
 6
Re: Question on faraday cage formula for hole size
you can take it as a hole smaller than a circle hole whose diameter less than 1/10 of the wavelength. If you made a square hole with a side of lambda/10, bisector/median of that square hole will be lamda*sqrt(2)/10 which is bigger than lambda/10

Advertisement

11th September 2017, 09:10 #3
 Join Date
 Jan 2008
 Location
 Bochum, Germany
 Posts
 45,127
 Helped
 13718 / 13718
 Points
 258,478
 Level
 100
Re: Question on faraday cage formula for hole size
As with any rule of thumb, the answers depends on the thickness of your thumb...
Please realize that there's no simple threshold. Smaller holes will still leak RF to some extent. You would perform an EM simulation with exact geometry to get the screening factor of a specific faraday cage.
As for the lambda/10 rule, looking at the hole diagonal seems reasonable as a first guess.

Advertisement

12th September 2017, 15:52 #4
 Join Date
 Jun 2006
 Location
 Pennsylvania, USA
 Posts
 200
 Helped
 28 / 28
 Points
 3,992
 Level
 14
Re: Question on faraday cage formula for hole size
I remember trying to use copper screen as a component shield, and the shielding effectiveness was poor, compared to a purchased solid shield. The rule of thumb did not work in that instance.
+ Post New Thread
Please login