[MLB-WIRELESS] node building

[Tyson Clugg]

On Wed, 2007-05-23 at 13:19 +1000, Rohan Malhotra wrote:
> I thought i might ask for recommendations on an omni 2.4ghz antenna on
> my roof. im presuming stock antennas (the stock antenna on a
> wrtrouter? )wont really cut it if i want to propogate this signal
> across my street. I was thinking something in the 9-15dB range for a
> dipole 360 omni should do the trick?

Be aware that the higher the gain on an omni-directional antenna, the
"flatter" the singal pattern.  Too flat and you might not get signal
where you need it.  To illustrate with ascii art:

< < < < < < < < < < < < < < < < < < < < < < < < < < | > > > > >
                                                    |
                                                 ___|____
< < < < | > > > > > > > > > > > > > > > > > > > /________\
    ____|___                            ________|[] || []|____
   /________\                          /          Node B
___|[] || []|____       Roadway       /
     Node A      \___________________/

Using high-gain omni antennae (eg: 15dB), the singal from Node A would
be directed at the wall/lower roof of Node B, while the signal from Node
B would be wasted way over the top of Node A.

A lower gain antenna gives a wider vertical range and might be better
suited, as it would also give access from ground level (probably
including inside the house).  Otherwise, you can tilt both omni antennae
to get a link.  If the terrain is very flat where you live and there are
few obstructions (eg: trees, tall buildings) then using a high-gain omni
might be a reasonable decision.

-- 
Regards

Tyson.