[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
sale.
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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