Hummm - All the antennas I know of are metal, and conduct at much less than 1 Ohm/Square.

Now, if you are talking about the enclosure over the antenna, I suggest you google for ESD paints or Anti-static paints.

Yeah I already did it and found few mantufacturers in US , UK and Taiwan but the resistivity those paints offers is too low, and some of the paints were only for the floors generally used in Patrol Station or Electronics Components production.

I need something which can discharge the staitc chrarge on the surface of antennas without generating sparks or effect of radiation pattern of the antenna.

Why would you do a paint, knowing that it could be scraped or abraded off?  

The outer surface of all my WiFi antennas are insulating, and there is no exposed antenna connection at all.

TTFN

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The application of our system to use in the mines where some flamable gases are present so if there is any static charge on the surface of the antenna then it can ignite the fire and can kill people. So we need something to cover our antennas with anti static material. We are using canvas but we are looking for some paints b'se canvas can still conduct when it becomes wet and affect the radiation pattern.

Well, well, well - I was wondering if this was tied to Intrinsic Safety! Doing a product right now on similar issues, but in our case, we're doing an additive to the plastic for our enclosure which will drop it into about the 100M Ohm range. The product happens to be cellular with internal antenna.

I assume you are buying an off-the-shelf antenna of some kind. You can get anti-static plastic sheets and films. I would suggest in you application, you contact a thermoform company, and have them thermoform a plastic sheet with the proper properties which you can apply over the antenna you have.

On a side note, a quick check of McMaster-Carr (mechanical/tool/materials distributor) showed they had Polyethlyene UHMW in anti-static dissipative film 0.005", 0.010", 0.020" thick part numbers 8327K11, 12, 13 , as well as thicker in thicker sheets. I just used a 3/4" thick material for a ESD production fixture, but I don't have data on the Ohms/square of this plastic. Any color you want as long as it's black.

Thanks for that. I will contact to that supplier about the anti-static dissipative film. Hope they have enough high resistivity.

Are you even sure that these antenna sheaths can generate ESD?  


Seems to me, such a possibility would mean death to the transceiver circuits attached to the antenna proper.

TTFN

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I recall Beech Aircraft used 300 ohm per square for their radomes to prevent static buildup.
Not to seem rude, but from who or from where did you get your requirement?  

I thought anti-static mats use a 500 kohm resistor to ground, but that's only after a large charge in a human is developed and he/she touches the anti static mat. Maybe your requirement comes from anti static mats??

If you are considering normal static buildup on radomes then the 300 ohm per square would be used.

kch

Well requirement came up from Mine projects where IS is the must for safety. Not haven't found any useful product so far.

Need anti- static material just to get rid of static charge on the antenna surface.

Why not just pull-off the plastic sleeve?

The only thing to watch out for would be to make sure that the pointy end doesn't poke out someone's eye.

how about this article. You could probably bond this to your radome.

Semi-Conductive Sponge Gasket Material for ESD Protection

Philadelphia, PA -- Stockwell Rubber Company, Inc. announces the availability of Semi-Conductive S4503-CON closed cell sponge for gaskets and cushioning pads in aerospace ground support, powder chemical processing and integrated circuit handling applications requiring ESD grounding. S4503-CON is a closed cell synthetic rubber sponge, formulated to have 500,000 ohms per square maximum surface resistivity.

Contacts:

General Information:
William B. Stockwell
USA
Phone: 800-523-0123
FAX: 215-335-9433
Website: www.stockwell.com


kch

Any chance you could sputter on a coating of metal.  A very thin metal, say a few microinches, would have a high resistivity.  Maybe nickle, tungsten, gold, etc.

I've had 0.5 and 2 uin of gold sputtered onto glass as a transmission line at RF frequencies. 0.5 is only slightly lossy, 2 uin is the industry standard minimum (or so I was told) and is pretty good as a microstrip conductor. So it's got to be really thin. I think the value needs to be so small it's not common to have less resistance than about 1000 ohm's/sq with metal deposition. Just a guess though.

kch

So, why not just pull-off the plastic sleeve?