wireless_PCI_connecting_cable

[ingles_man]

Does anyone know if the following is possible and if not why.

I'm going to build a cheap shotgun YAGI antenna to put on my
roof and it will have a N-type chassis connector with a low
loss co-axial pigtail drop (5cm / 2inches in length) going
directly to the circuit board of a Netgear PCI MA311 as I'm
trying to avoid signal loss. My Linux P.C is one floor away
from the roof or roughly 10ft - 3m.

Now here's the part I'm not too sure about, as mentioned the
Netgear card will not be sat in a PCI slot inside my Linux
Hostap computer it will be on my roof in a sealed plastic box
next to the antenna. I want to make (or buy if it's cheap and
out there) a connecting cable which would have a PCI connector
slot on one end and a PCI circuit board connector on the other
end. If this were to work does anyone know what's the maximum
length that this cable could be and could someone recommend a
cable brand.

I know that I could place a sealed P.C router box on the roof
but that's a waste of a P.C in my opinion.

Thanks in advance.

[x586]

Man don't waste days of your time trying to save 30 bucks, you'll just end up wasting the money trying to cobble something together and then have to buy the right stuff in the end.

Get a directional antenna and jumper cable (long pigtail) however long you need. You will be much happier in the end.

x586

[ingles_man]

Thanks your comment.

So what's the maximum distance for a pigtail drop? I've read tech pages on the internet that say you lose 1db for every foot of pigtail cable (using the best cable out there) and 1db for every connector used. Now the antenna will only produce a maximum signal of 12-15db. I need my pigtail to be 12ft in length so in theory I guess that I would have around 1-3db if I'm super lucky entering the Netgear card which will probably be an unacceptable super slow transfer data rate.

Any thoughts?

[x586]

I'm in a hurry and don't have time to look up the numbers, but the cable loss is way off. LMR400 cable which is probably the highest quality you would use (but not nearly the best there is) only looses something like 5db per hundred foot. Most connectors are probably in the 1-2db range for loss.

I'll look up the info when i get a chance, probably tonite or tomorrow and post some links for you.

x586

[x586]

http://www.universal-radio.com/catalog/cable/coaxperf.html cable signal loss chart

http://www.fab-corp.com/ best place I've found for cables

http://www.hyperlinktech.com/ best place I've found for antenna

http://www.netstumbler.com

Don't try to adapt the cables or make your own connectors get the right connectors made on them.

Don't think that an antenna makes the signal stronger, it concentrates it, but does not increase its power, in other words if a laptop right next to the 3db antenna that came with an AP gets a -15dbm reading through netstumbler and you hook up a 15db antenna you are not increasing your power. Standing right next to the antenna you'll still get a -15dbm reading, but when you get 100 yards away with the 3db antenna you see ocassional -95dbm(not useable signal) where as with the 15db antenna you see -60dbm (good signal). Hope I didn't confuse you here.

I consider anything over -50dbm(-49, -48(negative numbers) etc...) in netstumbler an excelent signal

Use the shortest cable you can, yet be sure it is long enough so that you don't come up two feet short. ( it's better to get 25' of cable, then to get 10' and need 12'

Below is a quick example on estimating your needs.
AP standard 3db antenna and you need to go 500 feet and through one wall to hit the AP.

LMR400 25' =2db loss
2 connectors 3db loss
Antenna 15db gain
So once it's all connected you have aprox. 10db gain.
about every 3.3db you dbl your distance, so the original antenna's (3db) gave you about 150' and one wall. Now you have 10db which is just over 200% more. 150' (plus the wall which is equal to about 100' no wall Line of sight). Now we can say 150+250+250=650' and still get a good signal.
The numbers are not anything close to exact just a rough and conservative guide to give you idea on distance.
I use the 14 dB Backfire Antenna from hyperlink and get a good signal at 650' with line of sight to a standard pcmcia card (Though the bridge I use is driving me nuts).

Hope this helps
x586

[ingles_man]

Thanks once again for your techie info and links.

Now I just need to buy the various bits and hopefully everything will work out fine.

:-)