usb adapter cantenna

I would like to build a cantenna that uses a usb adapter as the active
element so that I can avoid the problem of losses in a long run of
coax cable and just use cat5 instead. But I haven't been able to find
much info on best dimensions and usb adapter placement within the can.
What is the best diameter can and how long should it be? Should the
usb adapter poke through the back of the can in the middle or into the
side of the can like in a regular cantenna? If through the side, how
far from the back of the can?

I plan to use an inexpensive Zonet ZEW2501 usb adapter.

Has anyone built something similar and how did it perform?

Thanks for any help.

bjs555 <(E-Mail Removed)> wrote:
> I would like to build a cantenna that uses a usb adapter as the active
> element so that I can avoid the problem of losses in a long run of
> coax cable and just use cat5 instead. But I haven't been able to find

Are you talking about a game adapter at the end of cat 5, or a USB dongle
at the end of USB cable? cat 5 can go a lot farther. The USB should go 5
meters without an active repeater.

A friend was using a 6" diameter coffee can, which I found to have lower
gain than the 4" diameter two coffee can setup, but the larger can was
easier to point at an access point about two blocks away.

Bob Alston's coffee can
http://members.cox.net/tulsaalstons/Computer.htm
Clarence Dold's coffee can
http://www.rahul.net/dold/clarence/u...42-800x600.jpg
I used the turnpoint calculator to decide where to poke the hole.
http://www.turnpoint.net/wireless/cantennahowto.html

There are also many haphazard designs on the New Zealand page, using USB
dongles. http://www.usbwifi.orcon.net.nz/

Using a "standard" USB adapter, instead of the dongles, is on David
Taylor's site. http://www.nodomainname.co.uk/cantenna3/cantenna3.htm

--
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Clarence A Dold - Hidden Valley (Lake County) CA USA 38.8,-122.5

On Wed, 21 Sep 2005 22:53:42 -0400, bjs555 <(E-Mail Removed)> wrote:

>I would like to build a cantenna that uses a usb adapter as the active
>element so that I can avoid the problem of losses in a long run of
>coax cable and just use cat5 instead. But I haven't been able to find
>much info on best dimensions and usb adapter placement within the can.
>What is the best diameter can and how long should it be? Should the
>usb adapter poke through the back of the can in the middle or into the
>side of the can like in a regular cantenna? If through the side, how
>far from the back of the can?
>
>I plan to use an inexpensive Zonet ZEW2501 usb adapter.
>
>Has anyone built something similar and how did it perform?
>
>Thanks for any help.

A simple USB directional unit I made on the below page.

http://www.geocities.com/zoomkat/antenna.htm

Thank you both for the info and links. What I have in mind is the same
as Clarence Dold's coffee can. I want to use a USB dongle. But he
doesn't give any dimensions or formulas for determining them on his
page. I suppose I could just experiment some but I'd prefer to have a
calculated starting point. What kind of antennas do the dongles use?
Are there different types? Is there a way to solder a pigtail onto a
dongle?

Well, just reread your reply and I see that you are in fact Clarence
Dold and that you used the formulas in another link you gave to decide
where to poke the hole.

Thanks !!!

bjs555 <(E-Mail Removed)> wrote:
> Thank you both for the info and links. What I have in mind is the same
> as Clarence Dold's coffee can. I want to use a USB dongle. But he
> doesn't give any dimensions or formulas for determining them on his

The only calculation I used was the turnpoint page that I referenced.
http://www.turnpoint.net/wireless/cantennahowto.html

My coffee cans are 4" inside diameter. Plug that in to the turnpoint
calculator, and it will tell you that a wire radiator should be 1.7 inches
from the closed end of the can (measure inside). I made the assumption
that a USB dongle antenna should be at that same point.

The other dimension of interest is the length of the antenna element inside
the can. If I were putting the USB dongle in front of a simple reflector,
I would want it 31mm from the reflector. This suggests that the antenna
element of the dongle should be 31mm away from the wall of the can. The
antenna is at the tip of the dongle. Simply inserting the dongle inside
the can is conveniently near that dimension.

Here are some of the cans that I tried. I liked two 12 oz. Yuban cans the
best, but my friend likes the 3lb Yuban can, because it's easier to point.
According to the calculator, the 3lb can would be more efficient at
frequencies below the 2400 MHz of WiFi, but it works well for him.
The 12oz is even too large, but I couldn't get my hand inside a smaller can
to put the dongle in place. If this were a permanent setup, maybe you
could make it fit into a smaller can, but I was only playing, and I carry
the dongle with me, and don't normally use the can.

Can Diameter Length Wavlng 1/4wv TE11 TM01
3lb Yuban 6 7.5 5.50 1.38 1152 1505
Atkin's Bake 4 7 6.80 1.70 1729 2258
Hunt's Pasta 3.3125 5.5 9.40 2.35 2088 2727
Country Time 5 9 5.88 1.47 1383 1807
Nalley BigChunk 3.87 6 7.12 1.78 1787 2334
15oz coffee 4 5.5 6.80 1.70 1729 2258
Stagg Chili 3.3 4.2 9.50 2.38 2096 2737
12oz Yuban 3.875 5.3875 7.11 1.78 1785 2331

--
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Clarence A Dold - Hidden Valley (Lake County) CA USA 38.8,-122.5

bjs555 <(E-Mail Removed)> wrote:
> What kind of antennas do the dongles use? Is there a way to solder a
> pigtail onto a dongle?

Previously:
Jeff Liebermann <j...@comix.santa-cruz.ca.us> wrote:

http://members.cruzio.com/~jeffl/pics/wireless/DWL-122/
I removed the PIFA antenna, attached an SMA connector, and made some
bench tests for sensitivity, power out, and such.

--
---
Clarence A Dold - Hidden Valley (Lake County) CA USA 38.8,-122.5

This looks like a possibility. But I'd rather leave the dongle intact
like you did.

His site has a great name ... Learn by Destroying ... I do, but too
often by accident ... haha. If I keep the site name in mind, I know
I'll feel better next time it happens.

Thanks.

On Thu, 22 Sep 2005 05:18:02 +0000 (UTC),
(E-Mail Removed) wrote:

>bjs555 <(E-Mail Removed)> wrote:
>> What kind of antennas do the dongles use? Is there a way to solder a
>> pigtail onto a dongle?
>
>Previously:
>Jeff Liebermann <j...@comix.santa-cruz.ca.us> wrote:
>
> http://members.cruzio.com/~jeffl/pics/wireless/DWL-122/
> I removed the PIFA antenna, attached an SMA connector, and made some
> bench tests for sensitivity, power out, and such.

Well done! It's encouraging to read that you got a connection a mile
away with it!

One thing that bothers me about soldering a pigtail onto a circuit
board is that it may cause an impedance mismatch. What kind of circuit
is typically used to drive an antenna? A power transistor with low
output impedance? Some pictures I've seen show a dongle with an
antenna made of pc board traces. Where would I cut into the traces to
add a pigtail?

Thank you.

On Thu, 22 Sep 2005 23:13:40 +1000, "Pierre" <(E-Mail Removed)>
wrote:

>Not a Cantenna but very easy to make with good gain.
>
>http://homepages.ihug.co.nz/~redwood4
>
>Peter
>
>"bjs555" <(E-Mail Removed)> wrote in message
>news:(E-Mail Removed).. .
>> Well, just reread your reply and I see that you are in fact Clarence
>> Dold and that you used the formulas in another link you gave to decide
>> where to poke the hole.
>>
>> Thanks !!!
>

Not a Cantenna but very easy to make with good gain.

http://homepages.ihug.co.nz/~redwood4

Peter

"bjs555" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Well, just reread your reply and I see that you are in fact Clarence
> Dold and that you used the formulas in another link you gave to decide
> where to poke the hole.
>
> Thanks !!!