[kismac] Re: Wireless Link

  • From: Chris Weiss <chris.weiss@xxxxxxxxx>
  • To: kismac@xxxxxxxxxxxxx
  • Date: Mon, 17 May 2004 09:15:36 -0700

WRT a high-gain antenna. It sounds like you're on a budget - I've seen
a couple of projects where people have converted
DirecTV/Dish/Primestar dishes to high-gain directional antennas. If
you're in a neighborhood where people are moving frequently, you can
bet there's a couple sitting in garages waiting for the next yard

You might give that a try - I'd be curious to hear your results.

http://www.wwc.edu/~frohro/Airport/Primestar/Primestar.html is a
pretty good link, Google's got plenty more.

On Mon, 17 May 2004 10:09:54 +0200, Brad Knowles <brad.knowles@xxxxxxxxx> wrote:
> At 8:52 AM +0100 2004/05/17, Ian Beeby wrote:
> >  In many administrations, there is a fixed maximum effective radiated
> >  power for 802.11 systems, and this is calculated by taking the power
> >  output of the transmitter, subtracting the feeder and connector loss
> >  and adding the antenna gain.
>         Keep in mind that this varies greatly by country, region, etc....
> If you don't know what the EIRP limits are in your area, before you
> go playing around with high-gain antennas you should talk to local
> ham radio operators and experienced wireless network operators to
> find out what the limits are.  The last thing you want is to have a
> complaint filed against you for causing interference, and run the
> risk of possible criminal and civil action.
>         Here, the US is much less limited than Europe.  In the US, with
> clear line-of-sight and good high-gain antennas on both ends, you can
> legally get distances of 50-75km or more.  In Europe, it can be
> difficult to get more than 10-20km.  Carefully choosing your wireless
> cards (on both ends) so as to have maximum sensitivity can help a
> great deal.
> >                                So if you have a manufactured system
> >  with 20dBm eirp (effective isotropic radiated power) and replace
> >  the 7dB antenna with a 20dB one you'll strictly need to reduce the
> >  power output of the transmitter by 13dB - by a software setting or
> >  by adding more feeder loss.
>         Keep in mind that many manufactured systems are shipped with an
> EIRP that is significantly *below* the maximum allowed for that area.
> At issue here is not what is shipped, but what the total maximums are
> in your area and how different aspects of the overall system may need
> to be modified to stay under them.
> >  Sorry that this was a bit off topic.
>         I don't think it was off-topic at all.  I think it was a very
> good message, which delivered a lot of useful information.
> --
> Brad Knowles, <brad.knowles@xxxxxxxxx>
> "They that can give up essential liberty to obtain a little temporary
> safety deserve neither liberty nor safety."
>      -Benjamin Franklin, Historical Review of Pennsylvania.
>    SAGE member since 1995.  See <http://www.sage.org/> for more info.

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