cantenna casing

cantenna casing

Postby dubltap » Mon Jan 27, 2003 3:09 pm

would there be any signal degredation if I were to encase a cantenna in something like PVC? as much as I like the gain I hate the look of it. Hopefully the encasement would be a purely cosmetic change.
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Re: cantenna casing

Postby lincomatic » Mon Jan 27, 2003 4:42 pm

Originally posted by dubltap
would there be any signal degredation if I were to encase a cantenna in something like PVC? as much as I like the gain I hate the look of it. Hopefully the encasement would be a purely cosmetic change.


you can put anything you want on the outside. the signal only goes out the front. if you want to seal out the elements you can even put plastic over the front of it.
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Interesting....

Postby jeffrowe » Sat Mar 08, 2003 3:41 pm

I am not much when it comes to radio theory or antenna design...
in fact, its something i dont really understand at all...

but I follow directions good <wink>

So If I were to get a PVC Pipe of the correct inner diameter, and an end cap for it, then basically put a cantenna inside, and cap the open end with a PVC cap... the signal would still pass through the PVC? It woudl be like a short fat weatherproof YAGI in all except gain/db?

What about if I used sheet metal to form my own can? so that it better fit the cantenna specs and the PVC? or what about simply coating the insides of the pvc with metal?

This last one if an off the top of me head idea... I dont know what kind of metal I woudl use, or if it woudl be metallic paint, or what not... anyone want to comment? is it the metal? The reflective surface? what kind of paint/liquid metal/whatever woudl work???
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Re: Interesting....

Postby lincomatic » Sat Mar 08, 2003 4:14 pm

Originally posted by jeffrowe
I am not much when it comes to radio theory or antenna design...
in fact, its something i dont really understand at all...

but I follow directions good <wink>

So If I were to get a PVC Pipe of the correct inner diameter, and an end cap for it, then basically put a cantenna inside, and cap the open end with a PVC cap... the signal would still pass through the PVC? It woudl be like a short fat weatherproof YAGI in all except gain/db?

What about if I used sheet metal to form my own can? so that it better fit the cantenna specs and the PVC? or what about simply coating the insides of the pvc with metal?

This last one if an off the top of me head idea... I dont know what kind of metal I woudl use, or if it woudl be metallic paint, or what not... anyone want to comment? is it the metal? The reflective surface? what kind of paint/liquid metal/whatever woudl work???


for the cantenna, it doesn't matter what you put around it...even the shape of the outer casing doesn't matter...you could encase the thing in a concrete block if you like. the only impt thing is what you put in front of the aperture (the open end of the can) because that is where the signal enters...you don't want to put anything that would block the signal there.

the PVC casing is exactly what some of the commercial cantenna vendors do.

using sheetmetal is fine, as well as just painting conductive paint in the pipe. you could even contact cement aluminum foil into it. the performance would be the same.
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Postby MRK » Sat Mar 08, 2003 5:56 pm

One question. Look at this picture. Is this why you are talking about?

http://www.talkingpixels.org/stumbler/images/pringles_internal.jpg

Does anyone know if that will work?

Thanks!!

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Postby lincomatic » Sat Mar 08, 2003 9:31 pm

Originally posted by MRK
One question. Look at this picture. Is this why you are talking about?

http://www.talkingpixels.org/stumbler/images/pringles_internal.jpg

Does anyone know if that will work?

Thanks!!

-Mr.K



actually, in my prev post, i was referring to the waveguide-style
cantennas such as the one on this page:

http://www.geocities.com/lincomatic/homebrewant.html

i haven't actually built one of the circular "pringles-style" yagis,
but my understanding is that the can is not a waveguide, but rather only gives mechanical support. therefore, you wouldn't even need to use metal, nor would the diameter of the can matter. what does matter in this kind of design is the dimensions of the metal cup which the probe sits in, as well as the distance of the probe from the back of the cup. from what i can see in this photo, the design is wrong because the probe is just attached to the plastic and has no electrical connection to the metal reflector. of course, it's hard to tell due to the angle of the photo. in a proper design, the probe should be attached to the wall of a short metal cylinder which the back end of the yagi sits in.
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