On 5 Apr, 15:20, Walter Maxwell wrote:
On 5 Apr 2007 15:04:13 -0700, "art" wrote:





On 5 Apr, 14:12, (Richard Harrison) wrote:
Art wrote:

"I have mentioned 3 degrees but that was only by eye on print out for a
single element."

I have set the vertical angle of many highly directional dish feed horns
using a bubble level when the path was long. The best setting will be
horizontal so that the signal skims the earth when there are no
obstructions.

Never did subsequent adjustment of elevation angle for best signal ever
alter the bubble setting by one iota.

Why vertical or horizontal? To get the antennas parallel to each other.
That`s why.

All electrical charges exert forces on one another. At great distances,
the forces become vanishingly small. Even so, every effective antenna is
coupled to other conducting matter in its rdiation path to do work in
maintaining periodic motion of charges, however faint, throughout the
universe. Energy transferred by an antenna to the universe is said to be
radiated.

Radiation reflected by the ionosphere surrounding the earth is found to
be scrambled in its polarization (the direction of its E-field).

Energy directly communicated between line-of-sight antennas is most
effective when the transmitting and receiving antenna conductors are
parallel. Conversely, when they are cross-polarized, loss may exceed 20
dB.

Best regards, Richard Harrison, KB5WZI

No Richard, you are out of date.I'm sure that more about antennas is
taught
these days that has never showed up in Terman. On the tipping thing
many towers have multiple beamms on them and when one is added then
owners have to reset their antennas. Now ofcourse one can now move
them remotely until max polarity is observed. As far as parallel is
concerned, anytime you introduce reactance to the resonance to an
individual element you lose out on efficiency if polarity is a concern
qand in Termans time polarity was not that much of a concern. I truly
believe that most auguments on this newsgroup is because teachings of
yesteryear do not match up to present day teachings. With weather
forcasters they now direct R.F at a front first with horizontal
polarization and then with vertical polarization and then merge the
reflected pictures, thus it is imperitivethat polarization is dead on
for 3 D analysis of the weather front. Lots of things are done these
days that wasn't even thought about as little as 20 years ago such
that you must read iee antenna findings every month to keep up.
Art

Art, you still haven't explained what 'polarity' gain is. And what is maximum polarity? I learned polarity as
being plus or minus. Are there other 'polarities'?

Walt, W2DU- Hide quoted text -

- Show quoted text -

Walt, if you are looking for maximum horizontal or any other polarity
it can only be obtained by removal of reception of other polarities,
this maximum is obtained by having the radiator at 90 degree
multiples with respect to earth. You can prove this to your self
anytime by calculating max horizontal gain by progressively tipping a
dipole while keeping it resonant until the maximum is reached. If your
concern is for total gain without regard to polarity mix then the
vertical position total gain will equal the total gain of the tipped
dipole. The difference is that one arrangement has a mixture of
polarities where-as the tipped antenna will only provide a single
polarity. If another element or anything else is added near enough to
add reactance then the prior antenna must be adjusted to remove it,
thus the reason for remote adjustment which is much cheaper to
maintain rather than regular trips up a tower by maintanance men.
Hopefully Walter this will bring you up to date. I have no reason for
a 300 posting thread as I do not intend to write rev 3 of Reflections
or anything else.
Regards
Art