Measuring EMI shielding effectiveness with reflectance vs absorbance

[PolyOneTechie]

I am looking at EMI Shielding effectiveness testing and I would like to measure how a material is shielding Electromagnetic waves, qualitatively. Is there a way to measure how a material is shielding qualitatively and quantitatively (in dB)?

 

[ZapperZ]

I am looking at EMI Shielding effectiveness testing and I would like to measure how a material is shielding Electromagnetic waves, qualitatively. Is there a way to measure how a material is shielding qualitatively and quantitatively (in dB)?

Er... hum. Get a power meter sensitive to the range of EM wave that you're interested in, and put it on the other side of the EM source and measure?

Zz.

 

[sophiecentaur]

What is the form of this "shielding"? For good shielding, you need an enclosure, which makes it relatively easy to test - by putting a measuring receiver inside (self powered, preferably, to reduce the number of ways the unwanted signal can get in) and measuring with and without the box. Alternatively, you can put a (self-powered) source in the box.
Measuring the reflectance is much harder because you may need to look in all directions as there may be specular or diffuse reflection.
This all depends upon the sort of wavelength you're dealing with, of course. Give us a clue?