cantenna experiments

I looked up some specs for my radios. The Linksys WMP11 receive sensitivity is around -82 dBm and the Zonet ZEW2501 is about -85 dBm. I take it this means I need 6.31 uW to get a signal into the Linksys and only 3.16 uW for the Zonet. Does that sound right? I think there's probably some variation these is in these specs from unit to unit but the lower Linksys sensitivity could explain what I see.

Reply to
bjs555
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Make that pW? Told ya I don't get along with logarithms.

Reply to
bjs555

Have you tried rotating the cantenna at all?

Reply to
David Taylor

Polarity comes to mind. The can is three dimensional. You may have been rotating the aziumth and elevation, but the orientation of the antenna probe itself is also important. Try rotating the antenna on the long axis, so that the probe is vertical, horizontal, and other points in between. Especially if your small room is full of reflections, the optimum angle for the probe may not be obvious.

I like the Windsurfer. I have made several. I keep forgetting to leave enough "tab", so it takes me a while to assemble.

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Once upon a time From Don Widders:

You can just make an antenna out of the end of the LMR195. Remove about 3 inches of the plastic outer 'jacket' of the coax. Then pull the copper braid back over the remaining jacket. Get a piece of brass tubing at a hobby shop that will just slide over the braid and cut a piece of the tubing to 32 mm. Trim away any excess braid. Cut the center conductor so that it extends exactly 32 mm from where it exits from the braid.

Reply to
dold

I didn't see your "goofy" comment but the novel part was that the whole antenna other than the rear and the N type connector and probe was all cardboard. :)

It also happened to be the most effective antenna of the ones that I made.

David.

Reply to
David Taylor

On one system, I installed a Hawking antenna on a Netgear WG311, which has a tiny stock antenna. The "Hawking HAI6SDA Directional 6dBi 2.4GHz Antenna"

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is pointed at a Linksys BEFW11S4 that has a pair of Windsurfers.

It looks a little more professional than the cantenna. I used to have a pair of corner reflectors, but I caught grief from the local interior designer, and Jeff Liebermann, for the wrinkly tin foil.

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I read some mutterings from Don Widders today (posted in 2003, I wonder what happened to him), that said that the antenna should be centered in a corner reflector, because it might have corresponding reflections from three points, one on each side, and the fold itself. He felt that the antenna should be off-center a little.

Reply to
dold

At what connection speed and what type of modulation (CCK or OFDM)? The sensitivity varies with the connection speed and modulation type. If you're going to compare sensitivities, it has to be at the same speed and modulation type.

The variations from just the test equipment and test setup is at least

+/- 3dB. There's also some creativity in whether to use the US 10E5 BER (bit error rate) reference, or the ISO 10E6 BER. Also there are some that measure BER or PER (packet error rate).

The data sheet numbers for the complete radio is often exactly the same as that for the chipset data sheet. Well, that's impossible because of all the circuitry between the antenna connector and the chip. There's the diversity switch, 1 or 2 connectors, a chunk of coax, and often a matching network.

Reply to
Jeff Liebermann

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