433mhz Antenna (project) Transmitter only.

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pistol2012

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I have a small 3volt PCB that transmitts signals for a reed switch.

I need to place the small 7cm wire antenna into a steel pipe which is part of the project.

I know that I can't place the antenna within the steel pipe, as the signal will just not get out from within the pipe, however I was planning on cutting a groove say 5mm wide into the outer wall of the steel pipe, and then fill this with some silicone or polyurethane that is non conductive and then finally encase the antenna within this groove.
I plan on filling the remainder of the gap with more filler / silicone and then paint the steel.

I wanted to know if anyone with experience in the RF field can advise me if this will work, how it could work if at all possible?

Tas.
 

ampulman

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South Jersey
Would this be some type of weather instrument?

Anyway, without any real knowledge about antennas, this thought came into mind:

Think of the pipe with a groove as a letter C, with the antenna 'fixed' in the groove. To me, it looks like an antenna with a reflector. Since the antenna is small, could the pipe be positioned so that the groove faces the receiver? Further, since everything is small, how about adding a director?

Just my hair brained idea.

Amp
 

prcguy

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Depending on how big your pipe is a "slot antenna" could be a good choice. Basically a slot or rectangular opening is cut in a cylinder or even sheet metal and when fed and matched, the surrounding metal skin is the radiator. Here is an example of a slot antenna specifically designed for 433MHz and the dimensions can be changed quite a bit and it can still radiate well.
Slot Antenna for 433 Mhz by dxzone.com
prcguy
 

pistol2012

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Jan 21, 2012
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Thanks for the reply's.

Just looking at the slot antenna, I'm trying to think of how this works?
I basically have a 1200mm long galvanized steel pipe which is 90mm (outside diam.) rounded pipe.
This sits outdoors.

Does the antenna sit inside this pipe and radiate through the gap?
Ideally I'd like it to be vandal resistant. The electronics will be houses within the pipe & only be accessible through a security screw housing which is also part of this original steel pipe as described above.

Thanks for your assistance.
Tas
 
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