Testing RF shielding

Tim May tcmay at got.net
Thu Aug 23 08:21:51 PDT 2001


On Thursday, August 23, 2001, at 05:32 AM, Eugene Leitl wrote:

>>
>> Testing is key.  If you don't measure, you don't know.
>
> Renting time in HF testing facilities is expensive. Do you have
> suggestions for a simple sniffer type of instrument, that detects the
> amplitude of a radiated field? Do FETs pick up HF fine?

See my other post.

Radios work fine. Even the leakage of a computer at much higher than 
radio frequencies still causes interference (beat frequencies, emissions 
at the lower frequencies). A blaring radio that becomes dead quiet when 
placed inside an enclosure is a pretty good indicator of good shielding.

There are also readily available things that operate at multi-gigahertz 
frequencies. 802.11, if I recall correctly. A simple test with Wavelan 
or Airport could be rigged. (The protocol will likely fail long before 
the signal fades out by enough db to be interesting, so you may have to 
put some metering on an analog output somewhere. )

Renting a spectrum analzyer is another choice, if you're serious about 
this. (Or buying one on the surplus market.)

But, like I said, we used a portable radio to test our Faraday cages.

> I intend to build me a wearable based on a LART type of board
> 	http://www.lart.tudelft.nl/
>


A minor note. Your English is excellent, but  "I intend to build me 
a..." is not ideal grammar. "I intend to build myself a..." is the 
correct form. Your form is used by some native English speakers, though. 
Usually in the American south or rural west.

--Tim May





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