DIY Antenna Question!

Greetings,

First off, I want to thank everybody here for the wealth of
information. I went from being a wireless novice to, well, less of a
novice in no time reading the posts here!

The question I bring to you today is this, I have seen quite a few
ingenius solutions for USB wifi sticks being used with the notorius
"Chinese parabolic cookware".

This got me to thinking, I have the Edimax EW-7318USg which has a SMA
connected Rubber Ducky.

Does it make sense, (as in not cause a problem) to aquire a parabolic
cookware item, drill a small hole in the center, thread the SMA through
and then connect the Rubber Ducky?

I am lucky enough to be in a area that offers free WiFi, but signal
strenght is questionable at best, just thought this might be a neat
idea to try, just the run the concept past the experts first!

Many thanks!

RR


--
rockrabbit


- Talk to my Machine

On Sun, 23 Mar 2008 15:25:07 GMT, rockrabbit
<(E-Mail Removed)> wrote:

>The question I bring to you today is this, I have seen quite a few
>ingenius solutions for USB wifi sticks being used with the notorius
>"Chinese parabolic cookware".

Ahem... Salad bowl reflector. Very vegetarian:
<http://802.11junk.com/jeffl/antennas/Salad-Dish/index.html>
Just shove the USB stick into the plastic pipe. Slide it back and
forth for maximum signal. Flat bottom stainless salad bowls available
from Ace Hardware.

>This got me to thinking, I have the Edimax EW-7318USg which has a SMA
>connected Rubber Ducky.
>
>Does it make sense, (as in not cause a problem) to aquire a parabolic
>cookware item, drill a small hole in the center, thread the SMA through
>and then connect the Rubber Ducky?

Difficult to tell. There are two types of rubber ducky antennas. The
short 1/2 wave variety, and the same antenna with a 1/4 wave
decoupling sleeve. The top part is a 1/4 wave driven element, with a
1/4 coaxial sleeve forming a "coaxial sleeve" antenna and are the same
for both types. This is the short one:
<http://802.11junk.com/jeffl/antennas/coaxial/slides/coax-ant.html>
The longer one has an additional brass sleeve at prevent the coax
cable from radiating. Sorry no photo, as I haven't destroyed one yet.
The decoupling sleeve won't benifit much from an extra ground plane.
The shorter one probably will. However, the effect won't be huge in
terms of increasing the gain. All it does it prevent some of the
signal from radiating in odd and unwanted directions.

>I am lucky enough to be in a area that offers free WiFi, but signal
>strenght is questionable at best, just thought this might be a neat
>idea to try, just the run the concept past the experts first!

Methinks you would do better to abandon the rubber ducky, and build an
antenna that has some gain, such as a patch, panel, biquad, dish,
yagi, corner reflector, etc. I'm a big fan of the biquad mostly
because they're very easy to build (if you can solder). My favorite
instructions:
<http://martybugs.net/wireless/biquad/>
<http://www.vallstedt-networks.de/?Fotogalerien/quad2>
<http://pe2er.nl/biquad/index.htm>

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 2008-03-23 12:14:32 -0400, Jeff Liebermann <(E-Mail Removed)> said:
>>
>
> Methinks you would do better to abandon the rubber ducky, and build an
> antenna that has some gain, such as a patch, panel, biquad, dish,
> yagi, corner reflector, etc. I'm a big fan of the biquad mostly
> because they're very easy to build (if you can solder). My favorite
> instructions:
> <http://martybugs.net/wireless/biquad/>
> <http://www.vallstedt-networks.de/?Fotogalerien/quad2>
> <http://pe2er.nl/biquad/index.htm>


Methinks you are a genius!

BiQuad here i come!

Thanks!

--
rockrabbit


- Talk to my Machine

Wouldn't a ez-12 or EZ-F work well too? No extra connectors to buy?

http://www.freeantennas.com/projects...te2/index.html

http://users.picknowl.com.au/~gloaming_agnet/ant2.html



It would be interesting to see a comparision between the reflector and
a bi-quad.


Steve

On Sun, 23 Mar 2008 17:23:45 -0700 (PDT), seaweedsl
<(E-Mail Removed)> wrote:

>It would be interesting to see a comparision between the reflector and
>a bi-quad.

About the same gain and beamwidth. Small diameter antennas (i.e. less
than 2 wavelengths across) generally have the same capture area and
therefore the same gain. It could be a corner reflector, dish, patch,
biquad, or dipole array, it will have about 7-10dBi gain. The shapes
have a much bigger effect on higher gain antennas.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 (E-Mail Removed)
# http://802.11junk.com (E-Mail Removed)
# http://www.LearnByDestroying.com AE6KS

On 2008-03-23 12:14:32 -0400, Jeff Liebermann <(E-Mail Removed)> said:
>>
>
> Methinks you would do better to abandon the rubber ducky, and build an
> antenna that has some gain, such as a patch, panel, biquad, dish,
> yagi, corner reflector, etc. I'm a big fan of the biquad mostly
> because they're very easy to build (if you can solder). My favorite
> instructions:
> <http://martybugs.net/wireless/biquad/>
> <http://www.vallstedt-networks.de/?Fotogalerien/quad2>
> <http://pe2er.nl/biquad/index.htm>


So a quick question, now that I have this built, what is the best way
to use it... by this I mean, the antenna has to point at the source, so
how to I keep it vertical? The thought was to get two rubber coated
metal clips to form a tripod type stand.

make sense?

ideas?

thanks!

--
rockrabbit


- Talk to my Machine

On Tue, 25 Mar 2008 03:57:48 GMT, rockrabbit
<(E-Mail Removed)> wrote:

>On 2008-03-23 12:14:32 -0400, Jeff Liebermann <(E-Mail Removed)> said:
>>>
>>
>> Methinks you would do better to abandon the rubber ducky, and build an
>> antenna that has some gain, such as a patch, panel, biquad, dish,
>> yagi, corner reflector, etc. I'm a big fan of the biquad mostly
>> because they're very easy to build (if you can solder). My favorite
>> instructions:
>> <http://martybugs.net/wireless/biquad/>
>> <http://www.vallstedt-networks.de/?Fotogalerien/quad2>
>> <http://pe2er.nl/biquad/index.htm>

>So a quick question, now that I have this built, what is the best way
>to use it...

Ummm.... plug, point, adjust, and play. Monitor the signal levels on
your computer or use Netstumbler. Position the antenna for maximum
signal.

>by this I mean, the antenna has to point at the source, so
>how to I keep it vertical? The thought was to get two rubber coated
>metal clips to form a tripod type stand.

Methinks you'll need something more solid than that. The coax is
rather stiff. A real camera tripod will work. I stuffed a test
antenna into an electrical box:
<http://802.11junk.com/jeffl/antennas/biquad2/index.html>
which caused it to detune somewhat lower in frequency. Others ended
up inside kitchen plastic food storage boxes. The one on my bench is
held in place by two window shelf "L" brackets. The one I installed
on a neighbors roof is inside a glass bowl, with the coax cable shoved
through a hole drilled into a 2x6 piece of scrap wood. I built an
array inside a glass baking dish. User RTV for water proofing if
mounted outside. Lots of photos on the web. The basic idea is to NOT
put anything metallic in front of the antenna.

>make sense?

I like to make dollars, not cents.

>ideas?

Ideas are easy. Getting someone to fund them is more difficult.

>thanks!

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558