[Fwd: Re: Debugging a helical antenna installation]

mick stuckings mick at faceng.anu.edu.au
Mon Aug 6 10:12:15 EST 2001

If it's the cheap 50ohm ethernet, don't even bother trying, that's your 
problem. I tried this already :) You could easily be getting >50dB loss 
per 10m (I looked that up).
If you order a pre-terminated cable of LMR or similar and cut it in 
half, it's cheaper than buying the bits. LMR-400 is a good trade off 
with loss vs flexibility for longer runs (that's what others suggested 
to me), but it's not so good for connecting straight to the card as it's 
a bit thick.
For anyone interested here's what we did with webgears:
If anyone has any corrections to this I'd be happy to fix it :)

Alan Wilkie wrote:

>> What kind of cable is it? When we were doing this we made sure there was a
>> maximum of 2m of cable at each end and that was pretty expensive cable.
>> We're dealing with 2.4GHz here and you'd be suprised at the kind of cable
>> losses you can get.
> I'm not sure exactly what grade the cable is, all I know is that it's 50
> ohm coax.  I expected that there would be a reasonable amount of
> attenuation in the cabling, but the antennae should be about 14dBi gain
> and I thought there would be loads of signal to play with over the short
> distance we're trying to span.
>> With those full length ISA cards we had to chop the cable to get the
>> connector off and we had minor difficulties with the joints, but other than
>> that it seemed to work OK. From what I remember it's cable losses and
>> impedance that are your major issues.
> Thanks for that, we'll give it a try with shorter cables and try a
> different method of connecting the cables to the wireless cards.
> Alan

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