Dear OMs,
I have much to learn. Surely a dipole or Yagi has a certain maximum
height beyond which not much is to be gained by going higher even for DX -
QST did a study of the optimum height for a Yagi a number of years back.
A wavelength above ground was generally best though of course by going
higher lower angles were favoured and thus perhaps at times more distant DX.
Beyond a certain height though I doubt there is that much gained unless one
switches between antennas or stacks and this is well beyond the nature of
the original question. Of course we are talking about the HF spectrum.
I know boom length is important but are you saying that given a long
enough boom that a three element mono-band Yagi would outperform a six
element Monobander on a fifty foot boom. The additional elements surely
do add some forward gain - some. I know it may only be one to three dB
and hard to recognize in the QSB.
The tribanders will of course outperform the dipole in forward gain
and the difference is worthwhile though most of us are more concerned with
the improvements on the receiver side of the equation.
73 Doug EI2CN
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Jim
Thomson
Sent: 25 November 2014 18:52
To: towertalk@contesting.com
Subject: [TowerTalk] Yagi gain vs rotary dipole.
Date: Mon, 24 Nov 2014 20:46:14 +0100
From: "Peter Voelpel" <dj7ww@t-online.de>
To: "'Towertalk'" <towertalk@contesting.com>
Subject: Re: [TowerTalk] Yagi gain vs rotary dipole.
Hi Jim,
To get the same signal strength -4db compared to the 3el yagi on low angles
with your dipole that dipole must be mounted much, much higher then the yagi
and even higher with more elements on the yagi.
Tribanders at the same height as the 6 el monobander certainly will have
identical gain when the effective boom length is identical and enough
elements sitting on it.
I don?t build yagis for getting more gain above dipoles at high lobes, but
for low elevation angles and better receiving.
73
Peter
## Ok, what are u saying here. Lets say a 20m dipole and a 3-el 20m
yagi.... both at 70 feet.
At really low angles..say 0-10 deg..... will the 3-el yagi have even more
than 5.2 db of gain ??
Or put another way... even though 70 feet = aprx 15 deg take off angle of
main lobe.... does the
yagi exhibit more gain vs the dipole at angles below 15 deg ?
## anytime I have done yagi to dipole tests in the past..the difference was
astounding. I always
assumed it was cause the dipole was fixed...not rotatable... and not quite
broadside to the station.
Jim
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