Take a look at HFTA using flat ground ...
A stack of 3 element yagis at 35/70/105/140 shows between 6 and 7.5 dB
over a single 3 element yagi at 70 feet between 2 and 11 degrees. The
"crossover point" (where the higher lobe of the 70 antenna overtakes the
stack is around 16 degrees. The "three stack" (35/70/105) advantage is
between 3 and 4.5 dB over a similar 2 to 18 degree range.
Since HFTA does not model mutual impedance effects, the relative
difference is the same if one substitutes 4 element for 3 element
yagis.
73,
... Joe, W4TV
On 2021-09-03 3:58 PM, Peter Voelpel wrote:
With that stocking distance on 20m you will be lucky to get 3dB gain.
With 21m distance between 20m antennas you might reach 5.6dB
73
Peter
_____
From: jim.thom [email protected] [mailto:[email protected]]
Sent: Freitag, 3. September 2021 21:10
To: Peter Voelpel
Cc: [email protected]
Subject: Re: [TowerTalk] TH-7
4 x yagis stacked is only 4db ? Per the original article, it was a
flame thrower.
Jim VE7RF
On Fri, Sep 3, 2021 at 11:15 AM Peter Voelpel <[email protected]> wrote:
The stacking gain on 20m will be less then 4dB.
73
Peter
-----Original Message-----
From: TowerTalk [mailto:[email protected]] On Behalf Of
jim.thom [email protected]
Sent: Freitag, 3. September 2021 19:49
To: [email protected]
Subject: [TowerTalk] TH-7
Date: Fri, 3 Sep 2021 09:59:46 -0400
From: "Mike Ryan" <[email protected]>
To: <[email protected]>
Subject: Re: [TowerTalk] TH-7
<There was an op in Texas who mounted 4 of these on a rotating tower. There
<was an article in one of the ham magazines some years ago about it. But it
<was impressive. The TH7 has 5 elements on 10mtrs which soon will be more in
## It was on the front cover of a CQ magazine, back in the 80's. He
stacked em at 35-70-105-140'. With all 4 driven in phase, he was 20 db
louder than another ham, close by, who had just a single TH-7 up 70'.
I find that hard to believe, but that was what was reported.
The article was entitled.... "TH-28".
Jim VE7RF
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