Beam tilting
 

Is there any advantage to tilting a beam antenna up or down to match
the anetnna's elevation angle of maximum gain to the angle of the
received signal? It looks like the answer is yes but not enough to
justify the trouble/expense (unless you are tracking a satellite).

Ron, W4TQT

No.

Roy Lewallen, W7EL

Ron wrote:
Is there any advantage to tilting a beam antenna up or down to match the
anetnna's elevation angle of maximum gain to the angle of the received
signal? It looks like the answer is yes but not enough to justify the
trouble/expense (unless you are tracking a satellite).

Ron, W4TQT

No. The elevation angle of the first (or any) lobe is formed by the sum
of the main and the ground-reflected signals. If you tilt the antenna you
stop illuminating the two rays equally.

-- Tom




"Ron" wrote in message
. com...
Is there any advantage to tilting a beam antenna up or down to match the
anetnna's elevation angle of maximum gain to the angle of the received
signal? It looks like the answer is yes but not enough to justify the
trouble/expense (unless you are tracking a satellite).

Ron, W4TQT

Well, is there any dis advantage?

Roy Lewallen wrote:
No.

Roy Lewallen, W7EL

Ron wrote:

Is there any advantage to tilting a beam antenna up or down to match
the anetnna's elevation angle of maximum gain to the angle of the
received signal? It looks like the answer is yes but not enough to
justify the trouble/expense (unless you are tracking a satellite).

Ron, W4TQT

No, except maybe mechanically. The pattern of the antenna itself is
quite broad in the vertical plane. That is, its elevation pattern is
pretty fat unless it's a very long array, so tilting it in elevation
doesn't make much difference. The overall elevation pattern, except at
pretty high angles, is dictated by the ground reflection, which is
primarily determined by the height of the antenna above the ground.

If you're working satellites or otherwise line-of-sight where no
significant amount of ground-reflected signal hits the ground, then yes,
you want to point the antenna at the target. But again, unless the Yagi
is a very long one, its elevation pattern will be broad and you can be
pretty sloppy about the elevation angle.

A few minutes spent with a modeling program will illustrate these
effects clearly.

Roy Lewallen, W7EL

Murray wrote:
Well, is there any dis advantage?

Roy Lewallen wrote:

No.

Roy Lewallen, W7EL

Ron wrote:

Is there any advantage to tilting a beam antenna up or down to match
the anetnna's elevation angle of maximum gain to the angle of the
received signal? It looks like the answer is yes but not enough to
justify the trouble/expense (unless you are tracking a satellite).

Ron, W4TQT

Ron wrote:
Is there any advantage to tilting a beam antenna up or down to match the
anetnna's elevation angle of maximum gain to the angle of the received
signal?
Ron, I have a 12 element Yagi for TV (Horizontal) at 529 MHz and I find
tilting it down by about 10 degrees improves the reception by a
noticeable amount. The ground also slopes downhill by about 12 degrees
too (in the direction I'm looking). Putting the Yagi up higher is not as
good as having it about two feet off the ground with the downwards tilt.
The station is about 100 km away and the signal has to "bend" over a
range of hills 40 km from my location.

Alan