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Topic: way off topic wifi question (4 msgs / 95 lines)
1) From: Oolan Zimmer
The simplest answer to your question is:  yes, you can build longer antenna=
s
but they won't be as effective.  Bigger is not better.
A slightly longer answer to your question is:  you can build a half-wave
dipole antenna (connection point is center of wire) and it will work but
have a different impedance than the transmitter you are trying to hook it u=
p
to.   Longer antennas than that (full wave, etc.) are in theory exactly as
effective as the short antennas but in practice are less effective than the
short antennas because the extra wire has a non-zero resistance.
Next:  if you use good coax cable you can get the antenna farther from the
transmitter.  However, more cable = more signal loss, and enough cable ca=
n
actually cause the antenna to be out of tune for the frequencies you're
using.  I'd try real hard to put the transmitter (ie, wifi card) as close a=
s
possible to the antenna.  See cuwireless.net for an example box that's clos=
e
to the antenna.
Oolan Zimmer
ozimmer
ObCoffee:  I bet the right frequency of radio transmission at enough power
can roast coffee.  See microwave oven roasting.
On 4/24/06, Peter Zulkowski  wrote:
<Snip>

2) From: Peter Zulkowski
Thanks to all who responded  :)
Your replies sent me down pathways on the internet that I have not been 
to before, and I learned a lot.
It looks like:
You can build a /cantenna/, and get some decent gain, the 1/4 wave is 
better, and you get even more gain if you put the /cantenna/ in the 
focal point of a used satellite dish :)
You then have to run this signal to your wifi card which are available 
with external connections.
Another way is to get a wifi card that is built into a USB device (dongle).
It looks a lot like a thumb drive.
This you can mount either in a USB port on your PC, or...
get almost any length USB extender cable and mount it remotely :)
You could put this dongle in the focal point of an old satellite dish, 
or any likely parabolic reflector, and point it at your source.
PeterZ
Probably will get a dongle soon, here in LHC
Oolan Zimmer wrote:
<Snip>

3) From: Aaron
those USB wifi things are great peter.  It's about the size of a thumb 
drive and they do transmit / receive pretty good considering their 
size.  THey are pretty cheap too actually.
Aaron

4) From: raymanowen
"use good coax..."
At the frequencies involved, you couldn't afford it.  Waveguide is not so
terribly lossy and can be as directional as you want, but according to the
FCC regs and common sense, you can't just arbitrarily transmit any way you
want.
A parabola of revolution can focus a point source, which the wire radiator
is not. Also, if you put a metallic reflective surface in the vicinity of a=
n
rf radiator, the radiation resistance decreases and the mismatch slashes
energy transfer.
If you got some success, you'd need more yet. As is the past, it would lead
to cacophony, and a Hacker's dream.
Cheers -RayO, aka Opa!
Prior Planning prevents p poor performance-
On 4/26/06, Aaron  wrote:
<Snip>
--
"When the theme hits the bass, I dance the Jig!" - -Virgil Fox at the
Wichita WurliTzer


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