[TowerTalk] 15 meter yagi height for 6000 miles

[Cqtestk4xs at aol.com]

If you really want to see some very dramatic effects, I have some  from KH6 
where it was absolutely imperative to do HFTA.
 
Going south up a 13500 ft mountain I was on, even plotting with a  2000 ft 
tower it was impossible to get any lobes below 6 degrees.  However,  to the 
north I looked down into a 400 ft ravine across the street which gave me  9 
or so dBi gain on 80 meters.
 
Unless you live in southern FL or the KS plains, HFTA is really  helpful.
 
Bill K4XS/KH7XS
 
 
In a message dated 3/2/2012 6:51:05 A.M. Greenwich Standard Time,  
dotravel at aol.com writes:


Unless you are on totally flat ground for miles around you'll  need to run 
the Microdem program to import your exact location into HFTA to  actually 
get the correct gain and take off/landing angle info along with the  predicted 
historic DX angles that work.

Without knowing how your local  terrain affects the theroetical antenna 
height you won't have much to go  by!  

I can send you some examples of my QTH if you'd like --  tribander at 50' 
with a 225' drop-off to the East. . 

John NA6L  


-----Original Message-----
From: Bob K6UJ  <k6uj at pacbell.net>
To: Towertalk  <towertalk at contesting.com>
Sent: Thu, Mar 1, 2012 4:46 pm
Subject:  [TowerTalk] 15 meter yagi height for 6000 miles



Has anyone used  the HFTA program and can tell me the best height for a 15 
meter 
yagi for  6000 miles.
Assuming there aren't any hills obscuring the take off  angle.

The carribean is about 6000 miles from my qth and from  experimenting I 
have 
noticed that lowering the beam 
down from 90 feet  down to 50 feet it is markedly better for 15 meters.

I just bought the  new antenna handbook and plan to dive in and learn how 
to do 
the HFTA  myself but was
hoping someone else had an idea of the best take off angle  angle for 6000 
miles 
on 15.
I believe 50 feet is about 3/4 wavelength  high and gives me a 20 degree 
takeoff 
angle on 15.  
Hope this all  makes sense,  hihi.

Bob
K6UJ
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