On Tue, 14 Sep 2010 19:16:32 +0100, Justin C
wrote:

In article , Bruce in Bangkok wrote:

Yup. Built a super cantenna and ended up with approximately 4 times
the laptop alone signal. But as of two days ago we moved and the new
place is behind several concrete buildings which offsets the antenna
gain somewhat.

I've got a 4 ft. ex-satellite TV antenna that I am re-doing, using a
cantenna for the feed element that I'll install on a light pole,
hopefully soon, that ought to improve things up a bit.

So far I've built a "pringles", a corner reflector and a quad antenna
in addition to the various cantennas and no doubt that the cantenna is
the way to go..... but of course they are directional and the higher
the gain the more directional.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

I was talking about these with a radio engineer that I know. He said
that the coffee can (big Nescafe 2kg(?) size) is better than the
pringles can, with only one 'wrap' of the - what's it called, filament?
I can't remember the numbers that he claimed, but they were
considerable. Might be worth a try if you have time on your hands.

Justin.

The original Pringles can antenna was essentially just a yagi type
antenna. Had reflectors and directors made as washers inside the can.

The Cantenna, i.e. coffee can, is a wave guide type of design. There
are design formula on the web, but the diameter, length and position
of the single radiating element (they call it a probe) all interact.
My own experience was that a 3.5 inch diameter can worked best.

My findings, and I built four of them, was that the longer the tube
the more gain you got. The last one I built is 26 inches long and 3.5
inches in dia. I do not have an accurate way to test gain but the
software I have (Wavemon) shows a gain of 4 - 5 times over the built
in laptop antenna.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)