RE: How geographically big can a Wireless LAN be?

[Andy Laurence <andy@xxxxxxx>]

On Mon, 16 Sep 2002, Gerard McGovern wrote:
> > In a recent post on UKHA_Buy, the following statement was made
about 
> > 802.11b Wi-Fi compliant PCMCIA cards.
> > "With 24 dbi antennas at both ends, I have gone 8 miles with
no 
> > problems"
> 
> Someone please feel free to correct me, but isn't something that is
a
> good transmitter also a good receiver? This is the principal of
mobile
> phones and base stations. Base station very hi powered, mobile
phone
> not.

Correct.

> So in theory, you just need one decent antenna because if it can
> broadcast that far, it should also receive that far? But then again,
you
> could use two antennas to meet in the middle and I have just
> contradicted what I first said.

Sounds like you've answered your own question ;-)

To go a certain distance, you need a certain amount of gain.  This
must be 
distributed between the communicating radios.  For the sort of
distances 
mentioned, you will need an amount of gain at each end.  Last week, we
were going 70 yards through buildings using a 6dB panel antenna (1dB for
the connector puts us on the legal limit) at one end, and a standard card
with no external antenna at the other end.  We were quite chuffed
:-)

Andy
-- 
Building a wireless community network for Bristol
http://consume.andylaurence.co.uk
- updated 14/09
4x4 in town - bog brush for your teeth
NB: Alternate E-Mail - andylaurence at yahoo dot co dot uk

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