Indeed, HFTA is extremely helpful when optimizing antenna heights.
I have a sloping foreground advantage when working USA and use 5/5/5 on 20m.
Here is the HFTA diagram:
https://pbase.com/df3kv/image/86404961
At the moment only the highest antenna at 148 feet is on the tower and a
similar one on another tower at 82 feet.
With the present conditions the high antenna beats the lower antenna any
time.
Some years ago there were times when the lowest antenna of the stack alone
was the best to the east coast.
With the high antenna I am also able to hear almost any other German station
via back scatter.
73
Peter
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
Máximo EA1DDO_HK1H
Sent: Mittwoch, 15. Juli 2020 13:56
To: sawyered@earthlink.net; towertalk@contesting.com
Subject: Re: [TowerTalk] 20m monoband Yagi height
I have 2 - 20M 4 el yagis at 1/2wl and 1wl My terrain to EU is steep and
favorable. Within 200 ft of the tower base it drops off 110 ft.
I have extensively modelled with HFTA and done A LOT of on the air testing
both transmitting and hearing comparisons as well as receiving.
The stack is better about 75% of the time. The Top and Bottom are often
equal except for early morning openings which favor the top but probably
only for about 30 - 45 mins.
I am in Vermont so the angles are very different here than in many parts of
the country.
As a side note, I have 6 over 6 on 15M on the same tower - 3/2wl and
1/2wl.
The 1/2wl yagi by itself is the best or equal to the stack or top antenna
80%+ of the time. The stack the rest of the time. The top alone is NEVER
the best antenna although sometimes its equal to the bottom.
HFTA is amazingly accurate in predicting the above on the air performance.
Ed N1UR
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