Hi Bryan

It appears as though we have woken some major discussion... Someone may
even do the calculation for you!

The parabolic dish/grid "focuses" whatever power you start with. This
means more power or a higher gain antenna will mean more signal at the
far end. The result is additive. The power limitation is a legal one. I
dont remember whether it is 1W (30dBm) or 4W (36dBm) EIRP for
802.11/2.4GHz. The term EIRP refers to the power of the focused beam as
if it was the same level that would be obtained from a theoretical point
source antenna. In simple terms if you take the 4W EIRP and subtract the
antenna gain you will get the output maximum allowed at the transmitter.
In your case this would be;

36dBm(EIRP) - 24dB(antgain) = 12dBm or about 8mW

Keep in mind that you also have to allow for cable loss between the
transmitter and antenna. Numbers in the order of 6-12dB are not uncommon
so you would have to subtract this as a system loss. A 6dB loss would
bring your max transmitter power up to 18dBm or 32mW. Keep in mind that
advertising can be confusing. A bigger number on an antenna brochure
always seems better than a smaller one, but may be misleading. I dont
quite understand you statement about the grid antenna being adjustable
in power. (Also note cable loss affects the receiver too so you should
try to minimise it)

These are pretty low levels and are unlikely to upset any passing birds!
I wouldnt however sit in front of the dish for any extended length of
time. I'm just paranoid though!

re joining the antennas, yes just join the pigtails exactly as you
mentioned. Note others comments on the greater effectiveness of a
billboard reflector though. I didnt mention this thinking you wanted to
keep the visual effect small. I guess you could always disguise it as
something else though!

The higher the gain of the passive devices the larger the signal that
will be relayed. Higher gain means narrower or sharper directivity. The
problem is to work out how much you actually need without just trying it
and maybe failing. You could equally as well go for a couple of your
24dB grid antennas joined.

I should also mention that one of other major importances of a directive
antenna is to reduce multipathing or the signal bouncing off objects to
the side of the main path and getting to the antenna a little later than
the main signal. This can cause problems and slow your link down, may
even make it unusable.

Oh and speaking of which did you try bouncing the signal off the house?

I dont see the antenna mounting (separation) on both sides of the
utility pole as being a problem.

Also checking. There is a max distance parameter that will need tweaking
in a 802.11 setup. Make sure that is set to 2km or so.

Cheers Bob


Bryan Martin wrote:
The building location is maybe 500 feet away from where the repeater would
be. The parabolic grid is maybe 3000-3500 feet away from the repeater
location.