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Dee

Waterproof camera housings and antenna

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Hi all.

I'm about to build a waterproof housing for my camera/Tx assembly, but have hit a road block. I've build several waterproof housings for 35mm and video cameras, but nothing wireless...what do I do with the antenna?

Anyone have any ideas on how to externally mount (outside the housing) the antenna and then wire it to the Tx? Any wires can run through cable glands (keeps water out) but I've heard adding wire between Tx and antenna causes a drop in signal.

Any ideas on this would be greatly appreciated.

Dee

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I'm not sure if this would affect performance or impendance or what, but if you mount the tx with the connector through the case (using your favorite waterproofing method to seal around the hole) I wonder if you could just goop a bunch of silicon or other waterproof caulk into the connector before screwing in the antenna. Just be prepared to consider it a *permanent* installation :)

Regards,

Bill

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Why not use a commercial dipole antenna? The plastic shaft is watertight if you keep the connector part inside your case. Passing the shaft through a tight grommet with a bit of silicone or even light grease, such as vaseline, should keep the water out, assuming you don't go down too far.

Bruce

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That's a good point. This would prevent him from taking advantage of the articulated elbow on the antenna, but it would work.

Now to get really fancy, use a pipe threader to thread the entire length of the antenna (assuming it is one of the small whips with a consistent diameter plastic case), then use nylon nuts to 'capture' the antenna through the hole in the case. A bit of teflon tape, two rubber gaskets, and you are good to go, and it would be removable to boot!

I wonder if the diameter of the antenna matches any standard size nuts....

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Hi all.

I had thought of something close to these last two ideas, but wasn't sure what effect having part of the antenna inside the housing would do to signal strength.

Would it be negligible?

Thanks

Dee

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wasn't sure what effect having part of the antenna inside the housing would do to signal strength

Not a problem. Inside the shaft is a length of thin coax, the last 30mm or so is the driven element. Even if you position the shaft half in and half out of your box the driven element and much of the reflector (shield) will still be outside your box. Of course, range testing the setup will determine any observable signal loss.

Bruce

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Hi Dee:

Just a few inputs for you. Adding wire can reduce the transmitters signal if the wire is not a "low loss" type. Typically, the smaller the cable, the more loss. Next is frequency. The resonant frequency of water is 2.4 GHz which means the water will absorb more signal than other frequencies. This is why microwave ovens are on this frequency. Even still there are some people who are using 2.4 and can receive a signal from a depth of 18 inches with 800 mw of power.

Best, Ed

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