what type of adapter to use?

I got a SpeedTouch 570 router and I'm using the SMC USB adapter (the
little thumbsized one) to recieve, with extremely poor performance.

Would it make much of a difference if I get the larger type receivers?
(E.g Linksys, not powered by USB)

On 22 Dec 2005 23:32:10 -0800, "(E-Mail Removed)"
<(E-Mail Removed)> wrote:

>I got a SpeedTouch 570 router and I'm using the SMC USB adapter (the
>little thumbsized one) to recieve, with extremely poor performance.
>
>Would it make much of a difference if I get the larger type receivers?
>(E.g Linksys, not powered by USB)

It's not the USB (versus ethernet) that's causing the problem. It's
the tiny antenna that's in the thumb size USB devices.
http://802.11junk.com/jeffl/pics/wir...122/index.html
The gold PCB is the antenna. Some USB devices have even smaller
antennas.

First, some basics. A 3dB increase in antenna gain will increase your
range by 1.4 times. 6dB will double the antenna range. 12dB will
increase the range by a factor of 4.

Opinions seem to vary as to the gain of the tiny chip antennas. My
guess is about -3dB gain. The USB radios with the flip up antennas
have about 1dB gain. The typical wireless access point, running as a
client adapter, has a rubber ducky antenna. The gain roughly varies
with the length of the omnidirectional antenna.
4.5" 2dBi
6.0" 3dBi
11.0" 6dBi

So, if you go from a USB thumb device with -3dB antenna gain, to a
larger box with a 6" (stock) antenna with a gain of 3dB, you'll have a
6dB net increase in gain, which will double your range.

The real advantage of a larger box radio is that you can either
install a reflector to increase the gain even more:
http://www.freeantennas.com
or you can attach an external high gain antenna from a commercial
vendor. That's very difficult to do with a USB radio, which rarely
has an antenna connector.

If you go this route, be sure that whatever you buy has a "client
mode", where you can use the box as client radio. You might also get
away with an internal PCI card or PCMCIA card with an external antenna
connect.


--
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 Fri, 23 Dec 2005 00:32:43 -0800, Jeff Liebermann wrote:

> On 22 Dec 2005 23:32:10 -0800, "(E-Mail Removed)"
> <(E-Mail Removed)> wrote:
>
>>I got a SpeedTouch 570 router and I'm using the SMC USB adapter (the
>>little thumbsized one) to recieve, with extremely poor performance.
>>
>>Would it make much of a difference if I get the larger type receivers?
>>(E.g Linksys, not powered by USB)
>
> It's not the USB (versus ethernet) that's causing the problem. It's
> the tiny antenna that's in the thumb size USB devices.
> http://802.11junk.com/jeffl/pics/wir...122/index.html
> The gold PCB is the antenna. Some USB devices have even smaller
> antennas.
>
> First, some basics. A 3dB increase in antenna gain will increase your
> range by 1.4 times. 6dB will double the antenna range. 12dB will
> increase the range by a factor of 4.
>
> Opinions seem to vary as to the gain of the tiny chip antennas. My
> guess is about -3dB gain. The USB radios with the flip up antennas
> have about 1dB gain. The typical wireless access point, running as a
> client adapter, has a rubber ducky antenna. The gain roughly varies
> with the length of the omnidirectional antenna.
> 4.5" 2dBi
> 6.0" 3dBi
> 11.0" 6dBi
>
> So, if you go from a USB thumb device with -3dB antenna gain, to a
> larger box with a 6" (stock) antenna with a gain of 3dB, you'll have a
> 6dB net increase in gain, which will double your range.
>
> The real advantage of a larger box radio is that you can either
> install a reflector to increase the gain even more:
> http://www.freeantennas.com
> or you can attach an external high gain antenna from a commercial
> vendor. That's very difficult to do with a USB radio, which rarely
> has an antenna connector.
>
> If you go this route, be sure that whatever you buy has a "client
> mode", where you can use the box as client radio. You might also get
> away with an internal PCI card or PCMCIA card with an external antenna
> connect.

Jeff,

I have one of these too.. what are my options for replacing the antenna ?
Mount an SMA connector ? Which part does the centre coax go to ?

Doz

what about the router? do they differ in terms of transmission power?

On 23 Dec 2005 02:13:07 -0800, "(E-Mail Removed)"
<(E-Mail Removed)> wrote:

>what about the router? do they differ in terms of transmission power?

No, not much. The commodity wireless routers all transmit at about
+15 to +17dBm. There is a new class of router that has a built in
power amplifier that transits about +29dBm. They're also kinda
expensive at $600/ea. I consider those little better than jammers.
Yes, you'll hear such a high power access point at a much furthur
distance, but because your client radio is still transmitting about
+15dBm, the access point will not hear you at the same range. If you
want to increase range, then the transmit power has to be increased at
both ends of the link. All the a high power access point does is
create more interference for everyone.

The nice thing about improving the antenna (at either end) is that it
improves both the transmit and receive signal, thus improving your
range in both directions.
--
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 Fri, 23 Dec 2005 10:00:16 +0000, Doz <(E-Mail Removed)> wrote:

>I have one of these too.. what are my options for replacing the antenna ?
>Mount an SMA connector ? Which part does the centre coax go to ?
>Doz

One of "those"? Those what? I'll guess that you mean a DLink
DWL-122. I added a coax pigtail and external antenna to one of those,
but never had time to do any measurements. I would post a photo, but
it's on a neighbors roof and not easily accessible.

If you look at the photo at:
| http://802.11junk.com/jeffl/pics/wir...wl-122-01.html
The circuit board PIFA antenna has 3 connections. The one on the left
is ground. The one just to the right of this one is where the center
connection goes. The connection near the middle goes nowhere and is
just for mechanical support.

I would NOT try to solder a relatively large SMA connector in place of
the PIFA antenna. The leads will be too long and there's not enough
board area for a stable mechanical connection. It will break. A much
smaller SMB connector might work.

I unsoldered the antenna, and connected a .141 dia semi-rigid coax
pigtail to the left two connections.
| http://www.micro-coax.com/pages/prod...d141inches.asp
It is VERY important to keep the exposed part of the coax center wire
as short as possible. There is additional ground area on the circuit
board all around the RF connection and I used it liberally to maximize
the ground connection area. The coax came straight up from the board
(in the direction of where the PIFA antenna was replaced) in order to
minimize the exposed center conductor length. I forgot which side of
the board I installed the coax cable.



--
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 Fri, 23 Dec 2005 09:15:09 -0800, Jeff Liebermann wrote:

> On Fri, 23 Dec 2005 10:00:16 +0000, Doz <(E-Mail Removed)> wrote:
>
>>I have one of these too.. what are my options for replacing the antenna ?
>>Mount an SMA connector ? Which part does the centre coax go to ?
>>Doz
>
> One of "those"? Those what? I'll guess that you mean a DLink
> DWL-122. I added a coax pigtail and external antenna to one of those,
> but never had time to do any measurements. I would post a photo, but
> it's on a neighbors roof and not easily accessible.
>
> If you look at the photo at:
>| http://802.11junk.com/jeffl/pics/wir...wl-122-01.html
> The circuit board PIFA antenna has 3 connections. The one on the left
> is ground. The one just to the right of this one is where the center
> connection goes. The connection near the middle goes nowhere and is
> just for mechanical support.
>
> I would NOT try to solder a relatively large SMA connector in place of
> the PIFA antenna. The leads will be too long and there's not enough
> board area for a stable mechanical connection. It will break. A much
> smaller SMB connector might work.
>
> I unsoldered the antenna, and connected a .141 dia semi-rigid coax
> pigtail to the left two connections.
>| http://www.micro-coax.com/pages/prod...d141inches.asp
> It is VERY important to keep the exposed part of the coax center wire
> as short as possible. There is additional ground area on the circuit
> board all around the RF connection and I used it liberally to maximize
> the ground connection area. The coax came straight up from the board
> (in the direction of where the PIFA antenna was replaced) in order to
> minimize the exposed center conductor length. I forgot which side of
> the board I installed the coax cable.



That's the ticket.. Thanks for the info Jeff.

Doz

(E-Mail Removed) <(E-Mail Removed)> wrote:
> I got a SpeedTouch 570 router and I'm using the SMC USB adapter (the
> little thumbsized one) to recieve, with extremely poor performance.

Is the USB WiFi client in fixed location?
You could add a coffee can for a substantial boost in performance.

A friend was using a 6" diameter coffee can, which I found to have lower
gain than the 4" diameter two coffee can setup, but the larger can was
easier to point at an access point about two blocks away.

Bob Alston's coffee can
http://members.cox.net/tulsaalstons/Computer.htm
Clarence Dold's coffee can
http://www.rahul.net/dold/clarence/u...42-800x600.jpg
I used the turnpoint calculator to decide where to poke the hole.
http://www.turnpoint.net/wireless/cantennahowto.html

There are also many haphazard designs on the New Zealand page, using USB
dongles. http://www.usbwifi.orcon.net.nz/

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