WISP Antennas

What kind of antennas do wireless ISPs use? I thought maybe it was an
omni-directional due to the need to service people in a wide area, but I
understand that as gain increases the signal becomes more "doughnut-shaped"
(is this correct?) It seems that this would actually be less effective at
higher gain.

Seeker <(E-Mail Removed)> wrote:
> What kind of antennas do wireless ISPs use? I thought maybe it was an
> omni-directional due to the need to service people in a wide area, but I
> understand that as gain increases the signal becomes more "doughnut-shaped"
> (is this correct?) It seems that this would actually be less effective at
> higher gain.

No.
Consider a sphere of radius 1, with an antenna in the middle.
This has an area of 12.
An ideal omni antenna will broadcast in equal directions with equal
strength.
If you reduce the area of the sphere that the antenna is transmitting
to, then the strength goes up.
For example, if you look at the area of a stripe horizontally round
the sphere with a ten degree width, the area will be about a twelfth
of the whole area.
So, the signal strength goes up by a factor of twelve if you happen to
be horizontally in line with the transmitter.

The higher the gain of the antenna, the smaller the total angle into
which it's transmitting or recitevng.

As the gain goes up, the pattern becomes very doughnut shaped, as one
consumes more doughnuts
one becomes much rounder with the increase in gain of weight.

Really, - ISPs use fill in antennas, for small areas, pattern is omni, but
flattened vertically on top and bottom. In practice the patterns are very
lobed, scattered, not textbook at all, high gain antennas above 3 or 5 don't
really mean much. (Point to point is a different matter)

(E-Mail Removed)

"Seeker" <(E-Mail Removed)> wrote in message
news:E18nc.165851$(E-Mail Removed).. .
> What kind of antennas do wireless ISPs use? I thought maybe it was an
> omni-directional due to the need to service people in a wide area, but I
> understand that as gain increases the signal becomes more
"doughnut-shaped"
> (is this correct?) It seems that this would actually be less effective at
> higher gain.
>
>

Seeker wrote:

> What kind of antennas do wireless ISPs use? I thought maybe it was an
> omni-directional due to the need to service people in a wide area, but I
> understand that as gain increases the signal becomes more "doughnut-shaped"
> (is this correct?) It seems that this would actually be less effective at
> higher gain.

The doughnut shape is directly linked to an omni antenna, which many
WISPs use. The higher the gain the omni, the flatter the doughnut (thus
the more critical it is to aim the omni at the customers). Most WISPs
use sector antennas which slice the round "pie" into pie-shaped
sections, each with a little more thickness depending on the number of
wedges. You can hit more customers with 4 x 90 degree sectors than you
can with one 360 degree omni.