need your advice on wireless

[Vu Pham]

On Mon, 2007-06-18 at 09:21 -0500, David Bandel wrote:
> On 6/18/07, Vu Pham <vu at sivell.com> wrote:
> > On Thu, 2007-06-14 at 08:34 -0500, David Bandel wrote:
> > > On 6/14/07, Vu Pham <vu at sivell.com> wrote:
> > > > I have built some wireless ( 802.11a/b/g) networks but they are all in
> > > > house.
> > > >
> > > > Now I get involved into a project that requires me to cover a yard. The
> > > > size of the yard is about 1500'x 1000'.
> > >
> > > Approx the size of a football stadium  This is easier than inside a
> > > house -- should be no serious obstructions to block the signal. You
> > > may need an 8dbi omni or small sector antenna to increase signal
> > > coverage.   Just don't let water get into any antenna connectors.
> > >
> > > The biggest secret about wireless communication is not how much power
> > > you put out (how loud you shout), but how good you can hear the signal
> > > (how good your ears -- antennae -- are).  Most folks get this
> > > backwards.
> >
> > David,
> >
> > I look at the spec of the high-gain omni antenna and it shows they have
> > the beam width around 38 oV. This means the area right below the antenna
> > has no coverage. Is it ok to have a smaller antenna below the high-gain
> > one with different channel ( I am going to use 802.11g ) in order to
> > cover that area ?
> >
> 
> Won't be necessary.  The beam width you see is the 3db envelope.  That
> means as you leave that vertical range, you'll still see signal, but
> it will not be full strength.  As you move above or below, signal
> strength drops off rapidly.  So if you have an antenna 15 miles away
> at sea level and the omni is on a 3km high mountain, you might need to
> tilt the omni.
> 
> However, anything within the ground plane of the antenna (below that
> antenna out to a certain distance, that distance determined by the
> height of the antenna above the ground) will receive good signal.
> 
> You should not need a second antenna.
> 

Thanks, David. I hope that going thru this outdoor wifi project would
allow me to steal one tiny piece of your whole experience :)

Vu