I'm trying to setup a homebrew WiFi (802.11b/g) antenna for my IBM
Think Pad laptop. The coax run will be about 15" going to some home
brew antennas. I don't know the name of the antenna but it can be seen
at this url:

http://wireless.gumph.org/content/4/...s-antenna.html

I plan on running coax (2 lines) from the 802.11 card (internal mini
PCI)
to the rear top of the LCD display. I'll terminate with connectors and
attach the antennas when the laptop is open. Great plan but what about
coax losses? The output of the 802.11 card is 250mw.

Most WiFi antennas use RG174 coax - I've even seen mobile antennas
for WiFi with 10' runs of the stuff. Correct me if I'm wrong but
wouldn't
10' of rg174 at 5 ghz be so lossy that it would defeat the purpose of
the
mag mount mobile antenna?

Like I said, I only need about 15" from the output of the 802.11 card
to the antennas. What coax would be good? I'm worried about losses
but I also need to route the coax through the laptop and up the back
of the LCD display so size (dia) matters. I guess I'm stuck with RG174
but are there better choices? What would be the losses with 15" of it
into a matched load at 5ghz?

Basically, given the above conditions and with the need for both small
coax and teeny connectors, what would be your recommendations?

73's de Ken KG0WX

"KG0WX" wrote in message
oups.com...
I'm trying to setup a homebrew WiFi (802.11b/g) antenna for my IBM
Think Pad laptop. The coax run will be about 15" going to some home
brew antennas. I don't know the name of the antenna but it can be seen
at this url:

http://wireless.gumph.org/content/4/...s-antenna.html

I plan on running coax (2 lines) from the 802.11 card (internal mini
PCI)
to the rear top of the LCD display. I'll terminate with connectors and
attach the antennas when the laptop is open. Great plan but what about
coax losses? The output of the 802.11 card is 250mw.

Most WiFi antennas use RG174 coax - I've even seen mobile antennas
for WiFi with 10' runs of the stuff. Correct me if I'm wrong but
wouldn't
10' of rg174 at 5 ghz be so lossy that it would defeat the purpose of
the
mag mount mobile antenna?

Like I said, I only need about 15" from the output of the 802.11 card
to the antennas. What coax would be good? I'm worried about losses
but I also need to route the coax through the laptop and up the back
of the LCD display so size (dia) matters. I guess I'm stuck with RG174
but are there better choices? What would be the losses with 15" of it
into a matched load at 5ghz?

Basically, given the above conditions and with the need for both small
coax and teeny connectors, what would be your recommendations?

73's de Ken KG0WX

Hi Ken

Could you use a USB connected wireless adapter?? You can dismantel some
USB wireless adapters so their antennas are available to you for attaching a
coax and even a SMA if you have the ability to work with that small stuff.

Jerry

"Jerry Martes" wrote in message
news:NfKRf.7774$%e1.6453@trnddc05...

"KG0WX" wrote in message
oups.com...
I'm trying to setup a homebrew WiFi (802.11b/g) antenna for my IBM
Think Pad laptop. The coax run will be about 15" going to some home
brew antennas. I don't know the name of the antenna but it can be seen
at this url:

http://wireless.gumph.org/content/4/...s-antenna.html

I plan on running coax (2 lines) from the 802.11 card (internal mini
PCI)
to the rear top of the LCD display. I'll terminate with connectors and
attach the antennas when the laptop is open. Great plan but what about
coax losses? The output of the 802.11 card is 250mw.

Most WiFi antennas use RG174 coax - I've even seen mobile antennas
for WiFi with 10' runs of the stuff. Correct me if I'm wrong but
wouldn't
10' of rg174 at 5 ghz be so lossy that it would defeat the purpose of
the
mag mount mobile antenna?

Like I said, I only need about 15" from the output of the 802.11 card
to the antennas. What coax would be good? I'm worried about losses
but I also need to route the coax through the laptop and up the back
of the LCD display so size (dia) matters. I guess I'm stuck with RG174
but are there better choices? What would be the losses with 15" of it
into a matched load at 5ghz?

Basically, given the above conditions and with the need for both small
coax and teeny connectors, what would be your recommendations?

73's de Ken KG0WX

Hi Ken

Could you use a USB connected wireless adapter?? You can dismantel some
USB wireless adapters so their antennas are available to you for attaching
a
coax and even a SMA if you have the ability to work with that small stuff.

Jerry


Hi, Jerry and Ken

Pardon me for getting into this, but we would all like to know which USB
adapters (and cardbus adapters currently manufactured) can be taken apart
and fitted with an antenna connector. There are a number of PC card adapters
that have appeared in websites showing these modifications but the units are
mostly no longer manufactured. With metropolitan Wi-Fi coming in to various
municipalities lately, it is becoming more desirable to put up an antenna to
guarantee 100% connection when the AP is half a block away or behind a big
house or dense foliage.

Thanks for your help.

Chuck

"Chuck Olson" wrote in message
...

"Jerry Martes" wrote in message
news:NfKRf.7774$%e1.6453@trnddc05...

"KG0WX" wrote in message
oups.com...
I'm trying to setup a homebrew WiFi (802.11b/g) antenna for my IBM
Think Pad laptop. The coax run will be about 15" going to some home
brew antennas. I don't know the name of the antenna but it can be seen
at this url:

http://wireless.gumph.org/content/4/...s-antenna.html

I plan on running coax (2 lines) from the 802.11 card (internal mini
PCI)
to the rear top of the LCD display. I'll terminate with connectors and
attach the antennas when the laptop is open. Great plan but what about
coax losses? The output of the 802.11 card is 250mw.

Most WiFi antennas use RG174 coax - I've even seen mobile antennas
for WiFi with 10' runs of the stuff. Correct me if I'm wrong but
wouldn't
10' of rg174 at 5 ghz be so lossy that it would defeat the purpose of
the
mag mount mobile antenna?

Like I said, I only need about 15" from the output of the 802.11 card
to the antennas. What coax would be good? I'm worried about losses
but I also need to route the coax through the laptop and up the back
of the LCD display so size (dia) matters. I guess I'm stuck with RG174
but are there better choices? What would be the losses with 15" of it
into a matched load at 5ghz?

Basically, given the above conditions and with the need for both small
coax and teeny connectors, what would be your recommendations?

73's de Ken KG0WX

Hi Ken

Could you use a USB connected wireless adapter?? You can dismantel
some
USB wireless adapters so their antennas are available to you for
attaching
a
coax and even a SMA if you have the ability to work with that small
stuff.

Jerry


Hi, Jerry and Ken

Pardon me for getting into this, but we would all like to know which USB
adapters (and cardbus adapters currently manufactured) can be taken apart
and fitted with an antenna connector. There are a number of PC card
adapters
that have appeared in websites showing these modifications but the units
are
mostly no longer manufactured. With metropolitan Wi-Fi coming in to
various
municipalities lately, it is becoming more desirable to put up an antenna
to
guarantee 100% connection when the AP is half a block away or behind a big
house or dense foliage.

Thanks for your help.

Chuck

Hi Chuck

Although I dont have a part number for a USB wireless adapter, I can get
the number from my buddy's adapter. He replaced the built in antenna the
USB wireless adapter with a short coax to his Wireless antenna. I assummed
the adapters are available at places like Fry's.
I am using a different approach here at home. I put a Bridge behind
small satellite TV dish and suffered the loss associated with foot and a
half of coax loss to the illuminator. That allows me to run CAT 5 to the
computer.

Jerry

Well, I'm not just building *any* WiFi setup - I researched a bit and
found
on eBay what is generally agreed on to be one of the top 5 internal
802.11
cards. With up to 250mw output and external antenna, I plan on diving
into
a new hobby - wardriving.

I could just buy a USB WiFi adapter and crack open the case and hack it
with an external antenna but from what I've seen, both the low output
and
poor rx sensitivity seem to be quite common with these devices and that
is not what I want.

I did remember a bookmarked site which calculated the info I needed.
Turns
out that my coax in question will have about 1.7 db loss at 5ghz. Not
too bad.

Still, if anyone knows of a coax that is better than RG174 while being
about
the same size, please chime in with your comments!

Ken KG0WX