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RE: [Sheflug] wireless engineery types
Chris Johnson wrote:
> I can't remember where my notes from uni are so I'm hoping
> someone else can
> help on this. Just bought a wireless router box and the
> antennae (sp?) are
> removable. I have 2 questions
>
I have 2 questions also
what type of wifi router did you buy ? there are different types,
with different connectors.
Have you tried using kismet to measure the strength ?
You don't want to use ordinary coax, as its no good for the 2.4ghz
and will not perform well
LMR400 is the cable of choice, but its around £2+ per metre.
Its loss is about 0.2db per meter
Then you need a pigtail
( its a small cable that will convert the AP aeriel connection to
standard N-Type for other aeriels )
Legal limits on power output are 100 mW == 20dbm
(from man iwconfig dbm = 30 + log10(watts) )
you can easily get 10 db gain from an external aeriel and many access points
are at about 15db out of the box
so 15dbm + 10 db gain = 25 dbm output.
So you'd want 25m LMR400 to put you to legal limits again
( you might lose a couple of db in lightning arrestors and pigtails
though )
A good place for custom cable is
http://www.msdist.co.uk
a cheap place for aeriels is http:www.solwise.co.uk though I have found
their
cable to be variable in quality.
Maplins don't stock the parts in my experience. the RF connectors are quite
specialised
Alan Dawson
--
ICT Services
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