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[TowerTalk] 90' vs. 120' on 20 meters?

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Subject: [TowerTalk] 90' vs. 120' on 20 meters?
From: (Rob Frohne)
Date: Thu, 30 Apr 1998 11:20:27 -0700 (PDT)
Thanks for the comments Bill.  The terrain is flat in both locations
to at least 50 wavelengths, with the exception of some buildings.  In
the west direction about 10 wavelengths away is a long 1 story metal 
building.  I was worried about it, but I don't think it should
effect propagation in the north direction.  I've been on a hill
before and it does change things, however, in general it seems to me
a flat surface will provide a more predictable reflection and maybe
more coherent one as well.  I'm still puzzled....

Thanks & 73,

> Did you move 2 blocks down the road and 2 blocks down the hill?  
> My experience tells me that 90 - 110 feet is pretty darned good on 20 
> meters.  Most on this reflector would pick that height if they were 
> putting it on flat land.  
> What you didn't tell us is the terrain.  This makes all the difference.  
> If you live on irregular terrain, I would suggest buying a copy of 
> K6STI's TA (Terrain Analyzer).  If you are on a hilltop, 120' could very 
> well be worse that 90 feet.  For that matter, 90 feet is probably worse 
> than 60 feet.  
> At my place (hilltop with drastic slopes) I found that 90% of the time on 
> a stack of 204BA's (one at 105' the other at 55') that the lower antenna 
> was the best choice to Europe.  The bottom one was fixed so I couldn't 
> test in any other direction.  The stack was marginally better than the 
> lower antenna.  This was predicted by TA.  
> So now I have two 5 element 20 meter yagis on seperate towers, one at 55 
> feet and the other at 60 feet.  They are both exceptional performers.  My 
> experience on 10, 15 and 20 meters has shown that TA or YT (by N6BV) are 
> very good judges of what a hill will do to your HF antennas performance.  
> I highly suggest them.  You might be surprised what they tell you.
> 73
> Bill, W4AN
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