"Cantennas" to increase wifi transmitter range

What are some do-it-yourself ways that you can increase the range of a
wifi transmitter? I've heard stuff like you can make a "cantenna" by
putting a pringles can over the antenna, and that's supposed, but it
didn't work for me. I've also heard that this is illegal because of
the FCC. Is that true, and if so, why? I have a syslink wifi
transmitter/router/switch. It's supposed to work at 150 feet, but it's
definitely not doing that for me. It's in a wooden house. I have it
sitting in a room where there is a big cathode ray tube TV strait
through the room for it, could that me interferring with it? Even
though when it's turned off?

On 26 Nov 2005 22:44:55 -0800, "DJ Craig" <(E-Mail Removed)> wrote:

[alt.comp.networking.connectivity deleted because Newsguy claims it's
bogus]

>What are some do-it-yourself ways that you can increase the range of a
>wifi transmitter?

Better antenna or better location. Antennas can vary from simple
reflectors:
http://www.freeantennas.com
to various forms of corner reflector, biquad, dish, panel, patch,
yagi, omni, ad nausium antennas. Note that the antenna does not
generate any RF. It merely redirects it. If you want to increase the
antenna gain in one direction, there is a corresponding loss of gain
in other directions. Tailoring the antenna pattern to your
unspecified requirements is paramount in the selection of an
appropriate antenna.

>I've heard stuff like you can make a "cantenna" by
>putting a pringles can over the antenna, and that's supposed, but it
>didn't work for me.

Please tell me you didn't hear someone recommend putting a pringles
can over an omni directional antenna found one a typical access point.
That won't work.

>I've also heard that this is illegal because of
>the FCC.

If you're in Tennessee, why did you post this question to a UK
newsgroup?

It's not totally illegal to modify a wireless system by replacing the
antenna. Note that the rules changed on Nov 22. Section 15.204(c)(4)
proclaims:
Any antenna that is of the same type and of equal or less
directional gain as an antenna that is authorized with the
intentional radiator may be marketed with, and used with, that
intentional radiator. No retesting of this system configuration
is required.
What this means is that you can't change the type of antenna that is
supplied or use a version that has a higher gain, unless the
manufactory has bothered to type certify their system with the higher
gain antenna. In other words, most of the aftermarket antennas are in
violation of 15.204(c)(4).

>Is that true, and if so, why?

Why is it true or why is it so? I guess I have to answer both
questions. It's true because the FCC is deathly afraid that congress
might realize that the FCC's protectionist mentality toward large
monopolies, and the obvious and phenomenal success of unlicensed
services, might suggest to an elected official of moderate
intelligence that the FCC is largely obsolete and not serving any
useful purpose.

As to why it is so, the rule was established to all manufacturers to
offer for sale aftermarket antennas without requiring recertification.
Prior to about 2002, replacement of antennas was totally prohibited.

>I have a syslink wifi
>transmitter/router/switch.

That's nice. Any particular model number?

>It's supposed to work at 150 feet, but it's
>definitely not doing that for me. It's in a wooden house.

Fine. How far are you going? How fast? How many walls are you going
through? Wood is not transparent to RF. Got any foil backed
insulation in the walls? How about antique foil backed wallpaper?

Does it work when your unspecified client radio (it takes two to
tango) is in the same room as the Syslink something? In other words,
if you remove the walls and range issues, does the system work? It's
possible that either end is busted, misconfigured, or getting trashed
by intereference.

>I have it
>sitting in a room where there is a big cathode ray tube TV strait
>through the room for it, could that me interferring with it? Even
>though when it's turned off?

No. The TV set is probably not causing problems. The usual sources
of intereference are other 802.11b/g systems, municipal wireless
networks, microwave ovens, 2.4Ghz cordless phones, wireless security
cameras, and anything else that belches 2.4GHz.

--
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

"DJ Craig" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) oups.com...
> What are some do-it-yourself ways that you can increase the range of a
> wifi transmitter? I've heard stuff like you can make a "cantenna" by
> putting a pringles can over the antenna, and that's supposed, but it
> didn't work for me. I've also heard that this is illegal because of
> the FCC. Is that true, and if so, why? I have a syslink wifi
> transmitter/router/switch. It's supposed to work at 150 feet, but it's
> definitely not doing that for me. It's in a wooden house. I have it
> sitting in a room where there is a big cathode ray tube TV strait
> through the room for it, could that me interferring with it? Even
> though when it's turned off?


Do you have a big aquarium in the way? Seriously, that can interfere with
the signal.

No, our fish are in an outside pond and I don't think they eat radio
signals ;-)

But the TV is a 32 inch Sony CRT in the next room, right behind the
router. Of course it has a lot of big coils and a very thick glass
screen that might behave the same way as an aquarium. In fact it would
make quite a good aquarium.

Do you know if is possible to put an extension arial on the router.
This model has two antenae.

http://www.jefatech.com/product/MM24-5RD

The above site actually advertises an extension antenae for this
purpose. I might need two. But I would still be interested in the story
about a cantenna or any other Do-it-yourself method.

Joseph Stewart wrote in
vUjif.16716$(E-Mail Removed):

> "DJ Craig" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed) oups.com...
>> What are some do-it-yourself ways that you can increase the range of
>> a wifi transmitter? I've heard stuff like you can make a "cantenna"
>> by putting a pringles can over the antenna, and that's supposed, but
>> it didn't work for me. I've also heard that this is illegal because
>> of the FCC. Is that true, and if so, why? I have a syslink wifi
>> transmitter/router/switch. It's supposed to work at 150 feet, but
>> it's definitely not doing that for me. It's in a wooden house. I
>> have it sitting in a room where there is a big cathode ray tube TV
>> strait through the room for it, could that me interfering with it? Even
>> though when it's turned off?
>
> Do you have a big aquarium in the way? Seriously, that can interfere
> with the signal.

Likewise, if you put the access point in the loft to get the aerial as high
as possible to increase the range, beware of the header tank for the hot
water: it will absorb almost all the signal sent in that direction - as I
found when I put my parents' wireless adaptor in the loft: there was a huge
"shadow" on the side of the house shielded by the tank. The other problem
was overheating of the wireless adaptor in the summer heat up in the loft,
which isn't so much of an issue at this time of year now it's -2 deg C
outside!

Many people don't realise that a large tank of water (even if the tank is
made of plastic) will absorb wireless network signals because 2.4 GHz is the
resonant frequency of water - which is why food (which contains water) heats
up in a microwave oven and why this frequency is available for short-range
wireless networking because it is useless for long-range transmission since
water in the atmosphere will attenuate the signal.

DJ Craig wrote:
> http://www.jefatech.com/product/MM24-5RD
>
> The above site actually advertises an extension antenae for this
> purpose. I might need two. But I would still be interested in the story
> about a cantenna or any other Do-it-yourself method.
>
Take a look at my web site for information on the cantenna I used with
great success.

http://members.cox.net/tulsaalstons/...Adapter%20.htm

http://members.cox.net/tulsaalstons/...-cantenna2.htm

If you do a search for "cantenna" in newsgroup alt.internet.wireless you
should find LOTS of info (I found 341 entries).

Bob

In article <(E-Mail Removed) .com>, DJ
Craig says...
> What are some do-it-yourself ways that you can increase the range of a
> wifi transmitter? I've heard stuff like you can make a "cantenna" by
> putting a pringles can over the antenna, and that's supposed, but it
> didn't work for me.

That's because you have to actually make an antenna out of the pringles
tin, not just stick it over the existing antenna, fuckwit.

> I've also heard that this is illegal because of
> the FCC.

You're posting to a UK group and the FCC have nothing to do with us.



--
Conor

"You're not married, you haven't got a girlfriend and you've never seen
Star Trek? Good Lord!" - Patrick Stewart, Extras.

Thus spake DJ Craig:

> But the TV is a 32 inch Sony CRT in the next room, right behind the
> router. Of course it has a lot of big coils and a very thick glass
> screen that might behave the same way as an aquarium. In fact it would
> make quite a good aquarium.

It's not the aquarium's glass that causes problem for wireless signals; it's
the water. Water is death to wireless signals. That's why trees are such a
hinderance to wireless; leaves "look" like little bags of water to the
wireless devices.

If the TV is such a big concern for you, experiment by putting your router on
top of the TV. Does that make your reception better?

> Do you know if is possible to put an extension arial on the router.
> This model has two antenae.

Many antennae available to connect to your router.
--
Please, no "Go Google this" replies. I wouldn't
ask a question here if I hadn't done that already.

DaveC
(E-Mail Removed)
This is an invalid return address
Please reply in the news group

In article <(E-Mail Removed) .com>,
(E-Mail Removed) says...
> What are some do-it-yourself ways that you can increase the range of a
> wifi transmitter? I've heard stuff like you can make a "cantenna" by
> putting a pringles can over the antenna, and that's supposed, but it
> didn't work for me.

It's a bit more complicated than that - there are plenty of websites
that tell you how to do it properly.

> I've also heard that this is illegal because of
> the FCC. Is that true, and if so, why?

Here in the UK we don't worry too much about the FCC :-)