On Fri, 24 Oct 2008 08:21:57 -0700 (PDT),
ab9il.worldwide@gmail.com
wrote:
>Okay guys and gals, it's done. After lots of e-mails asking about a
>good Wi-Fi antenna that is simple to build and still beats the
>cantennas and wok-tops: http:www.ab9il.net/wlan-projects/
>wifi6.html . Gain is around 15 dBi, and it is made of wood, wire, and
>a pigtail.
>
>Enjoy!
>
>Phil
>http://www.ab9il.net/
<http://www.ab9il.net/wlan-projects/wifi6.html>
Nice but not enough info to actually build one. There's no detail on
the driven element. Some general comments:
1. The center of the Wi-fi band is 2442 MHz, not 2450 Mhz
2. Round the ends of the elements. Don't square them off. The cut
length should be to about 2/3 the radiused end. See Antennex yagis
for what I'm talking about. It increases the usable bandwidth
dramatically with no loss in gain. The wire guage you're using will
result in a rather narrow bandwidth. I prefer 1/4" copper water pipe.
3. When I click on the right hand antenna pattern image, I get 404
not found.
4. The directivity pattern looks really odd (if not wrong). It
should look something like this:
<http://www.hyperlinktech.com/multimedia/datasheets/DS_HG2415Y.PDF>
Note that for 14.5dBi gain, the commercial antenna is about 462 mm.
Yours is 419 mm long. Close enough.
5. What is the boom made from? It looks like wood. Hopefully it's
not conductive or all you calcs are wrong. With a conductive boom,
the element length is measured to go around the outside of the boom.
Wood also has a bad habit of absorbing moisture. I watched a 440MHz
yagi that I build from a 2x2 fir boom slowly change vSWR pattern over
several months as the wood absorbed and released moisture. I don't
expect much of a problem with your size boom, but it is something that
you should watch for.
6. Oops. I didn't see the "next step" at the bottom of the page. May
I suggest you make it an obvious button that's duplicated at the top
of the page. The 2nd page details the construction, but doesn't show
how the pigtail is attached, whether a balun is used, and whether any
matching is required for what is normally a 200 ohm folded dipole.
7. I can feed the design into 4NEC2 and see what it looks like, but
don't have the time. (sorry).
8. Have you done any measurements? Even a Netstumbler comparison
with a known reference antenna is useful.
9. You might wanna post it to rec.radio.amateur.antenna for
additional comments.
Good luck.
--
Jeff Liebermann
jeffl@cruzio.com
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
15 Element Wi-Fi Yagi 
Linear Mode
