Please see subject line-- Help, Wifi Antenna-- on
alt.binaires.schematics.electronic
for a picture of my concept.
Looking to combine Helical antenna and Wifi adapter card in one unit.
My experience is limited to MW bcb. I know there are many pitfalls at
2.4Ghz, so I'm looking for feedback on how to do this properly.
I'm using the following page as my guide.
http://www.wlan.org.uk/jhecker.html

This is to extend the range of my laptop computer.

Mike

amdx wrote:
Note that in almost all places there are legal limitations on EIRP
(Effective Incident Radiated Power). In plain English, the more
you narrow a signal, the stronger it becomes.

Since you did not say where you are, I'll mention the two places I
know for sure. In the U.S. WiFi EIRP is limited to 1 watt for
mobile/portable use (e.g. laptops) and 4 watts for fixed links.

With a 100mW source and a reasonablyshort cable the famous Pringles can
antenna would be illegal for mobile/portable use and probably illegal
for fixed links. It happened to be developed by an FBI agent in the
process of an investigation, so he was covered, you may not be.

Here in Israel it is limited to 100mw EIRP, so unless you have
a very long cable, any gain antenna would be illegal. Someone wrote
up (in Hebrew) and posted on a web site his use of a similar
antenna. It's not obvious to the casual reader that he did it
in an area under the jursidiction of the IDF (Israeli Army) and
got permission from them.

Geoff.

--
Geoffrey S. Mendelson, Jerusalem, Israel gsm@mendelson.com N3OWJ/4X1GM
IL Voice: (07)-7424-1667 U.S. Voice: 1-215-821-1838
Visit my 'blog at http://geoffstechno.livejournal.com/

"amdx" <amdx@knology.net> wrote in message
news:e2a88$46a76893$18d6b40c$7378@KNOLOGY.NET...
Hi Mike

You sure find some great information on the Web.

I consider this article Jason Hecker publishes
http://www.wlan.org.uk/jhecker.html to be ALL the instructions anyone
would need for constructing a 20 dB directivity WiFi antenna. I am looking
for some feedback from you on its performance.

If you plan to investigate basic effects of changing size and shape of
Helix antennas, EZNEC sure makes Helix antenna investigation easy.

I am just curious, what kind of coax and connectors are you using, and,
?how much coax?.

Jerry

Bear in mind that 2.4GHz is also an amateur band where no erp limits exist!!

Jeff

On Wed, 25 Jul 2007 18:12:26 +0100, Jeff wrote:
Oh , really ?! cite!

Jeff wrote:
Only 802.11b/g channels 1-6 fall in the amateur allocation of 2390-2450 MHz.

If operating under amateur regulations you must identify by CW, phone,
RTTY or TV image every 10 minutes or less (see 47CFR97.119), your
transmissions must be intended for reception by another licensed amateur
station or station authorized to communicate with amateur stations (see
47CFR97.111), that has to be the only reasonable way to effectively
communicate, no other radio service available that accomplishes the same
communications (see 47CFR97.113) and you have to use the lowest power
level capable of accomplishing the communications (see 47CFR97.313).

See http://www.access.gpo.gov/nara/cfr/w...7cfr97_01.html for
specific regulations.

gwatts wrote:

I forgot to mention amateur communications cannot be encrypted, so no
https, see 47CFR97.113 again.

That may be true but to use it that way legally you would need an
amateur license, and this is not just a paperwork exercise, you have to
pass FCC exams covering electronics and radio theory (plus laws and
regulations) to get one. For most people, it's not an option.

Allodoxaphobia wrote:

"gwatts" <gwatts@frontiernet.net> wrote in message
news:6wMpi.12851$B25.3670@news01.roc.ny...
Most amateurs set the SSID of the access point to their call sign, since this
is beaconed numerous times per minute. Apparently that's close enough to RTTY
to keep most people happy.

Sure.

This particular regulation creates plenty of argument, since realistically the
vast majority of activity on amateur radio frequencies these days could be
just as readily accomodated by either cell phones or the Internet; I doubt the
FCC has cited anyone for violating this rule for decades now.

Indeed, although this too is subject to debate because people will argue that
while, e.g., 1W will get them a bit error rate of 10%, they "need" a near-zero
bit errorr rate and therefore transmit at 100W.

You point about not being able to use HTTPS or other encrypted protocols is
probably the most significant change in moving from using WiFi in an
unlicensed mode to using it under the amateur radio service's rules. However,
note that it is perfectly OK to obfuscate *authentication* data such as
passwords -- packet BBSes have done this for decades.

---Joel

"Barry Watzman" <WatzmanNOSPAM@neo.rr.com> wrote in message
news:46a7981e$0$30632$4c368faf@roadrunner.com...
Very few people would have significnat difficulty passing the technician class
license exam that's needed to operate on 2.4GHz. Indeed, there are many
month-long (meet a couple times a week) classes and even weekend "cram"
classes that have near 100% success rates in getting people their tickets. A
passing score is 80%!

"Jerry Martes" <j.jmartes@verizon.net> wrote in message
news:KGKpi.5345$Da.3887@trnddc07...
alt.binaires.schematics.electronic
in it you will see I'm trying to avoid connectors and cable carrying 2.4Ghz
R.F.
Thanks for being the only poster to have anything near a response to my
post.
Mike

"Jeff" <jeff@local.host> wrote in
news:46a784ab$0$1347$834e42db@reader.greatnowhere. com:

Not in most civilized countries.

2.4 Ghz is unlicensed, not unregulated.

On 7/25/07 10:12 AM, in article
46a784ab$0$1347$834e42db@reader.greatnowhere.com, "Jeff" <jeff@local.host>
wrote:

Hams have a segment of it, but not 2.4 to 2.5.

However, if the wifi ends up in the ham band in a commercial purpose there
will be hell to pay when they get caught, ham or not.

Jeff wrote:
Well.. not all the 802.11b/g channels are in the amateur band, and even
there, there is a power limit (transmitter output power, though, not
EIRP), so you could conceivably fire up your 1500 Watt transmitter into
a 20dBi antenna and blast away.

There is the other rule about minimum power needed for communication,
though.

"mike" <amdx@knology.net> writes:

Do note that many people's Usenet servers do not carry any binaries
groups, so they will be unable to look at your picture. If you were to
place the photo on a server where it can be accessed by HTTP or FTP,
these people would be able to get it. Many ISPs provide some web space
served by their own web server, and there are free photo hosting sites
like flickr.

Dave

"amdx" <amdx@knology.net> wrote in message
news:e2a88$46a76893$18d6b40c$7378@KNOLOGY.NET...
The Wifi Helical antenna is an awful lot of work, and the performance of
even long structures on PVC tubing is vastly disappointing. The easiest 15
dBi (my measurement) gain antenna is the Biquad. In fact, if you make the
biquad with circular instead of square loops, the construction is even
easier, and there's no problem measuring with all those bends - - just one
wavelength of straight wire in a circular loop for each section - -
http://www.wikarekare.org/Antenna/bicircle.html But try to keep a 50-ohm
coaxial configuration all the way to the feed points as in
http://homepages.ihug.co.nz/~redwood4/ It isn't necessary to keep the
polyethylene insulation - - for a short length of air insulated coax, the
tubing ID should be 2.25 times the center conductor OD for 50 ohms
impedance.

If you are like me, you will probably want to build the Helical anyway - -
just to see, and perhaps to compare against the two easiest wifi antennas
with decent performance - Biquad and Waveguide
http://www.saunalahti.fi/elepal/antenna2.html The easiest waveguide can is
the 83mm ID one you get with the 28oz size of Bush's Baked Beans or any of a
number of other products like canned spaghetti sauce or family size
Spaghettis.

See if you can get a USB Wi-Spy Spectrum Analyzer module, too - - try to
find one of the original (no external antenna - - cheaper) versions, and
just put it in your own shielding enclosure and make your own modification
to cut the path to the built-in antenna so that you can run a small coax to
a connector on the box for your own external antenna connection. This kind
of modification has been made by others - -
http://www.metageek.net/default.aspx...5&view =topic
scroll down to the post by pe2er on 9/9/06 showing how to connect a coax to
the board. I used a type N connector on my enclosure because it's universal
and strong, and filtered the three USB supply and signal wires with
feed-thru capacitors so no RF can enter the enclosure through these other
paths. Use Metageek.'s Chanalyzer software to run the Wi-Spy module - -
preferably version 2.0 before the current 2.1.4 came out, since the need for
compatibility with both the $199 Wi-Spy and the $399 Wi-Spy made operation
with the $199 Wi-Spy somewhat unsatisfactory. Maybe you can ask Metageek to
allow access to previous Chanalyzer 2.0 for owners of the older units. Why
do you want all this? So you can make accurate measurement of the
differences between antennas, using a reference 1/2-wave dipole, or the
standard RPSMA antenna you find on most Wifi Routers. The dB calibration of
the Chanalyzer display is very accurate.

Chuck W6PKP

On Jul 25, 8:13 am, "amdx" <a...@knology.net> wrote:
FYI, alt.internet.wireless discusses this topic often.

I prefer the biquad antenna, which you can augment with a dish. I have
a short-cut method to build this antenna. With a combination of these
photographs and this link, you should be able to figure it out.

http://martybugs.net/wireless/biquad/
http://www.lazygranch.com/images/wifi/wifi_bq_1.jpg
http://www.lazygranch.com/images/wifi/wifi_bq_2.jpg

Note you don't need to make the loop a square. Use a circle of the
same circumference.

There is a disadvantage to using the helix. It will receive both
horizontal and vertical polarization. Most sites just send in one
polarization. In busy areas, the same channel will be used in
different sites with different polarity. Now if you use the helix to
illuminate a dish, then the circular polarization is fine and perhaps
desirable. That is, you could sniff out signals without the
attenuation associated with having the wrong polarization.

"mike" <amdx@knology.net> wrote in message
news:52fd5$46a7a24c$18d6b40c$21937@KNOLOGY.NET...

Hi Mike

My computer skills are really lacking. I dont know how to view your
images. I do spend alot of time learning about antennas. One of my
buddies tells me that he had poor results with the helix he built from the
instructions you cited. This site seems to have been better for my buddy.
http://www.pa0hoo.tk/.
Is it practical for you to use a Bridge at the input terminals of your
gain antenna so that the coax loss is minimized? That way, the antenna
(+Bridge) is connected to the computer with CAT 5 cable.
If it isnt too complicated, tell me how to view your images.

Thanks
Jerry

On Wed, 25 Jul 2007 12:09:30 -0700, Joel Kolstad wrote:
But, I suppose that believing, as did an earlier poster:
"Bear in mind that 2.4GHz is also an amateur band where no erp limits exist!!"
is acceptable for these No-Code, No-Klew Licensees?

Spaghettis should read Spaghettios


"Chuck Olson" <chuckolson01@REMOVETHIScomcast.net> wrote in message
news:M8OdnVWDR5DJMTrbnZ2dnUVZ_r-vnZ2d@comcast.com...