$8 Wi-Fi reflector

I have a difficult time resisting temptation:
| http://802.11junk.com/jeffl/antennas...reflector.html
It's not a parabolic reflector. It's circular or rather part of a
circle. The circular shape reflects back on itself resulting in a not
very directional but also not totally useless antenna pattern. I'll
model it with 4NEC2 when I stop chuckling. I guess I should also do
some gain testing.

Of course, the aluminum reflector can be bent easily into something
resembling a parabola. Well, maybe not so easily as it's fairly
stiff. $8 at your local camping store. Mounting contraption
included. Coleman 295A720T.
| https://www.ebizenterprise.com/index...D&ProdID=70752

--
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

I have two antennas on my linksys.
Is one side transmitting and one side reciving?
Or will one side tx & rx, Can I use this and beam one side to my frieind





"Jeff Liebermann" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> I have a difficult time resisting temptation:
> | http://802.11junk.com/jeffl/antennas...reflector.html
> It's not a parabolic reflector. It's circular or rather part of a
> circle. The circular shape reflects back on itself resulting in a not
> very directional but also not totally useless antenna pattern. I'll
> model it with 4NEC2 when I stop chuckling. I guess I should also do
> some gain testing.
>
> Of course, the aluminum reflector can be bent easily into something
> resembling a parabola. Well, maybe not so easily as it's fairly
> stiff. $8 at your local camping store. Mounting contraption
> included. Coleman 295A720T.
> |
https://www.ebizenterprise.com/index...D&ProdID=70752
>
> --
> 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

"Rich" <(E-Mail Removed)> hath wroth:

>I have two antennas on my linksys.

What model Linksys is connected to your two antennas? WRT54G?

>Is one side transmitting and one side reciving?
>Or will one side tx & rx, Can I use this and beam one side to my frieind

>> | http://802.11junk.com/jeffl/antennas...reflector.html

Each antenna is part of a diversity reception system. The Broadcom
chipset in the Linksys WRT54G will select which antenna heard the last
good packet received. When selected, it is used for both TX and RX.
You can control which antenna is being used with alternative firmware,
but not the stock Linksys WRT54G firmware.

At one time, there was a problem with pointing one antenna to the
neighbors and using the other for local coverage. It would only
appear when transfering large files between the two wireless
connections. I'm fairly sure this is no longer a problem on current
Broadcom chipsets.

If you use two different antennas (or one reflector) you effectively
break the diversity algorithm. There's a really good chance that the
router will select the wrong (weaker) antenna based on simple
probability as to which antenna happens to be active when a packet
arrives. If it's the weaker antenna, then you will have rotten signal
reliability until the signal completely disappears and the router
decides to scan for a better antenna. Someone found a nifty article
explaining the problem of using different antennas, but I can't find
it.

Before you spend $8 on an obvious abomination, you might look at:
http://www.FreeAntennas.com
http://www.freeantennas.com/projects/Ez-10/
which is a much better design.

--
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

BEFW11S4



"Jeff Liebermann" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> "Rich" <(E-Mail Removed)> hath wroth:
>
> >I have two antennas on my linksys.
>
> What model Linksys is connected to your two antennas? WRT54G?
>
> >Is one side transmitting and one side reciving?
> >Or will one side tx & rx, Can I use this and beam one side to my frieind
>
> >> |
http://802.11junk.com/jeffl/antennas...reflector.html
>
> Each antenna is part of a diversity reception system. The Broadcom
> chipset in the Linksys WRT54G will select which antenna heard the last
> good packet received. When selected, it is used for both TX and RX.
> You can control which antenna is being used with alternative firmware,
> but not the stock Linksys WRT54G firmware.
>
> At one time, there was a problem with pointing one antenna to the
> neighbors and using the other for local coverage. It would only
> appear when transfering large files between the two wireless
> connections. I'm fairly sure this is no longer a problem on current
> Broadcom chipsets.
>
> If you use two different antennas (or one reflector) you effectively
> break the diversity algorithm. There's a really good chance that the
> router will select the wrong (weaker) antenna based on simple
> probability as to which antenna happens to be active when a packet
> arrives. If it's the weaker antenna, then you will have rotten signal
> reliability until the signal completely disappears and the router
> decides to scan for a better antenna. Someone found a nifty article
> explaining the problem of using different antennas, but I can't find
> it.
>
> Before you spend $8 on an obvious abomination, you might look at:
> http://www.FreeAntennas.com
> http://www.freeantennas.com/projects/Ez-10/
> which is a much better design.
>
> --
> 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

I am trying to get a 1/4 mile to a wusb54g


"Jeff Liebermann" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> "Rich" <(E-Mail Removed)> hath wroth:
>
> >I have two antennas on my linksys.
>
> What model Linksys is connected to your two antennas? WRT54G?
>
> >Is one side transmitting and one side reciving?
> >Or will one side tx & rx, Can I use this and beam one side to my frieind
>
> >> |
http://802.11junk.com/jeffl/antennas...reflector.html
>
> Each antenna is part of a diversity reception system. The Broadcom
> chipset in the Linksys WRT54G will select which antenna heard the last
> good packet received. When selected, it is used for both TX and RX.
> You can control which antenna is being used with alternative firmware,
> but not the stock Linksys WRT54G firmware.
>
> At one time, there was a problem with pointing one antenna to the
> neighbors and using the other for local coverage. It would only
> appear when transfering large files between the two wireless
> connections. I'm fairly sure this is no longer a problem on current
> Broadcom chipsets.
>
> If you use two different antennas (or one reflector) you effectively
> break the diversity algorithm. There's a really good chance that the
> router will select the wrong (weaker) antenna based on simple
> probability as to which antenna happens to be active when a packet
> arrives. If it's the weaker antenna, then you will have rotten signal
> reliability until the signal completely disappears and the router
> decides to scan for a better antenna. Someone found a nifty article
> explaining the problem of using different antennas, but I can't find
> it.
>
> Before you spend $8 on an obvious abomination, you might look at:
> http://www.FreeAntennas.com
> http://www.freeantennas.com/projects/Ez-10/
> which is a much better design.
>
> --
> 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

"Rich" <(E-Mail Removed)> wrote:
>I am trying to get a 1/4 mile to a wusb54g

Not going to happen, get a pair of WAP54G devices and some gain
antennas and you might be able to bridge things...

William P.N. Smith <(E-Mail Removed)> hath wroth:

>"Rich" <(E-Mail Removed)> wrote:
>>I am trying to get a 1/4 mile to a wusb54g

>Not going to happen, get a pair of WAP54G devices and some gain
>antennas and you might be able to bridge things...

Agreed. The Coleman lantern reflector might gain about 6dBi at best.
Without additional gain at the WUSB54G end, it won't work. See the
FAQ for link calculations at:
| http://en.wikibooks.org/wiki/FAQ_for...k_Calculations
My guess is:
TX power = +15dBm (at BEFW11s4 end)
TX coax loss = 0dB
TX ant gain = 6dBi (lantern reflector)
Distance = 0.25 miles
RX ant gain = 0dBi (at WUSB54G end)
RX coax loss = 0dB
RX sens = -84dBm (at 12Mbits/sec)
Fade margin = Unknown
Plugging into:
http://www.terabeam.com/support/calculations/som.php
yields 12.8dB fade margin. That's not enough. It should be at least
20dB for reliable operation. The missing 7.8dB of gain will need to
be added for this system to work reliably. It cannot come from
reducing losses as those are at zero already. It must come from
better antennas at both ends. My guess(tm) is you'll need a better
antenna at both ends.
--
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

Jeff Liebermann <(E-Mail Removed)> wrote:
> I have a difficult time resisting temptation:
> | http://802.11junk.com/jeffl/antennas...reflector.html
> It's not a parabolic reflector. It's circular or rather part of a

$8? Yee gods, man! That's a bloody fortune!

It does look like it's straight, at least.

I tried the "original" parabolic reflector from freeeantennas
http://www.freeantennas.com/projects...ate/index.html
but it never wanted to stay squared. It would twist off axis, which I
think would make it hard to set up a NEC model ;-)

Are you going to try to shape yours to a parabola?
What are the dimensions of the reflector?
And of course you want to remove or disable the other rubber duckie, unless
you want to invest another $8 to reflect both.


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

Rich <(E-Mail Removed)> wrote:
> I have two antennas on my linksys.
> Is one side transmitting and one side reciving?
> Or will one side tx & rx, Can I use this and beam one side to my frieind


You will not have much success aiming in two different directions with a
stock BEFWS11. If the client radio can connect on the poor antenna as well
as the strong one, it might not use the strong one. On the other hand,
there's no harm in trying.

http://www.freeantennas.com EZ-12, Windsurfer reflector.
printed on photo paper for thick stock, with aluminum foil glued to the
sail, provides a substantial boost in signal. Leave the tabs longer than
on the printout, to make them easier to stick thought the sail.
http://www.rahul.net/dold/clarence/EZ12-windsurfer.jpg

With 54g connections, I find that watching the "current bandwidth" in the
Windows perfmon.msc is a pretty good signal indicator.
start-run-perfmon.msc
+ Performance Object = Network
Numbers agree with dslreports.
+ Performance Object = TCP "current bandwidth"

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

On Mon, 6 Feb 2006 21:10:25 +0000 (UTC), (E-Mail Removed)
wrote:

>Jeff Liebermann <(E-Mail Removed)> wrote:
>> I have a difficult time resisting temptation:
>> | http://802.11junk.com/jeffl/antennas...reflector.html
>> It's not a parabolic reflector. It's circular or rather part of a
>
>$8? Yee gods, man! That's a bloody fortune!

Yeah, I know. It's more expensive than a coffee can.

>It does look like it's straight, at least.

Oh yes, it's very stiff.

>I tried the "original" parabolic reflector from freeeantennas
>http://www.freeantennas.com/projects...ate/index.html
>but it never wanted to stay squared. It would twist off axis, which I
>think would make it hard to set up a NEC model ;-)
>
>Are you going to try to shape yours to a parabola?

I was thinking of cutting a parabolic template from a 4x6 chunk of
lumber and beating the reflect to shape with a rubber mallet.
Blacksmithing isn't taught much these days, but it has its uses.

However, I'm going to wait a bit before beating it into a parabola. I
wanna see what pattern results from the existing partial cylinderical
reflector. I don't expect much in the way of gain or pattern, but it
seems like an easy thing to add that doesn't require tools.

>What are the dimensions of the reflector?

Too small. It really should be larger. I'll post the dimensions when
I get back home.

>And of course you want to remove or disable the other rubber duckie, unless
>you want to invest another $8 to reflect both.

Yep. Diversity and two different antenna do not work unless you hide
the antennas from each other.

--
# 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