Will anti-static plastic interfere with GSM/GPS signal

[dennis013]

Hi, i am a novice trying to design a casing for GPS/GSM enabled key chain. I have two questions for which i was hoping some one could help me with.

First one is. Is it really nescassary to make a plastic casing for electronics anti-static?

Second one: Does the anti-static grain interfere with the reception of GSM or GPS signal? Maybe like a faraday's cage?

If some one could answer these i would be very grateful!
Thanks very much in advance!

 

[Skogsgurra]

I don't think it is necessary to make it anti-static. But better safe than sorry.

If you look at the impedance of space (the medium that radio waves travel in) and the impedance of anti-static plastic, you will see 377 ohms for space and probably megohms for anti-static plastic. That alone indicates that you will not have any problems.

But stand by for someone that has actually tried. I haven't.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[Skogsgurra]

Correction, the impedance of plastic is lower - it is the parallel impedance caused by the conductive additive that is in the megohms region. So, the difference between ordinary plastic and anti-static plastic should not be noticable.

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[dennis013]

Thanks that is already a great help!

 

[zappedagain]

The trick I learned and used in the past is to put a cup of water and a sample of your plastic in the microwave until the water boils. If your plastic is still cool it didn't absorb any of the RF energy; if it is hot it is attenuating the RF signals that pass through it.

You need the cup of water to ensure that there is something in the microwave that is absorbing the energy; otherwise some microwaves will shut off if they don't sense the energy being absorbed and you'll get a false reading.

I've always figured if I stay about 0.1" away from a metal case that the gap is wide enough to stop an 8KV spark (the IEC standard). I believe that logic should apply for plastic too.

John D