In article , wrote:

With a dipole, you are depending on the null to minimize the undesired
signal and have little gain in the direction of the desired signal.

With a yagi, you still have the null (assuming a proper yagi) plus
additional gain in the desired direction. The net result is the ratio of
the signal strengths of the desired to undesired signals becomes greater.

Agreed. With a Yagi one might get the best desired-to-undesired
signal strength ratio by pointing the antenna somewhat to one side or
the other of the transmitter. This could reduce the "desired" signal
somewhat, but could put the "undesired" signal path right in one of
the antenna's deep nulls. Most Yagis having a modest number of
elements have a wide-enough beam angle to give you a fair amount of
wiggle-room in the aiming.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
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Dan Jacobson wrote:
"A Yagi doesn`t help, as we are depending fully on the null."

Dan also wrote:
"I am the owner of great sheets of metal."

If "your favorite FM station, 90 Mhz," differs in direction from its
interfering "competition, and only with a horizontal dipole at a certain
azimuth", a Yagi made by adding a director and a reflector should
increase signal to noise ratio.

Great sheets of metal can be used as a corner reflector for a favored
dipole. A 90-degree reflector can give about 10 dBd gain. A 60-degree
reflector can give about 2 dB more gain than the 90-degree reflector.

J.D. Kraus documented the corner reflector, Proc. I.R.E., 28, 513-619,
November 1940. Consult Kraus, "Antennas" for complete information, 1950
edition, page 328.

Best regards, Richard Harrison, KB5WZI

I used to live on the very fringe of an FM stations coverage area, probably
outside their intended cover area. Had great succes with 4 stacked 2 element
Yagis(think of old TV antennas). I and a guy down the street who had a
hundred foot tower were the only people in the county who could get the
station reliably. This was pretty good since this was the only FM station
that serviced the area at that time.


"JGBOYLES" wrote in message
...
Assume there is only one spot on your hilly land that you can pull in
your favorite FM station, 90 Mhz, over the competition, and only with
a horizontal dipole at a certain azimuth. A Yagi doesn't help, as
we are depending fully on the null.

Commercial FM stations are vertically polarized, cause most of the
people
that listen are in cars. I have found this to be true in my homebrew
antennas
(at least around here). You might try changing the polarization, and see
if
that helps.

Not sure why you think a yagi won't help. A 3 or 4 el. yagi with a good
F/B
and proper polarization will be a big improvement over the end nulls of a
dipole.

Using great sheets of metal for a dipole will increase the bandwidth,
but
that is not what you are looking for. Using the great sheets of metal for
a
screen reflector, or corner reflector could produce some big improvements.

73 Gary N4AST