[TowerTalk] Beverages and verticals

Jim Brown jim at audiosystemsgroup.com
Sat Mar 18 12:31:39 EDT 2017


On Sat,3/18/2017 9:16 AM, Bill via TowerTalk wrote:
> 1.  I can make them any height, but am considering 10 feet  with a rise to maybe 14 over the driveway.  Thoughts on the height, and the "hump' over the driveway?
Lower height makes them work to a higher frequency. Mine are over 
irregular terrain, with intended height varying between 6 and 12 ft, and 
often drooping to 2-3 ft when a limb hits it. They are still working on 
20M, and I used the EU Beverage on that band before I had aluminum in 
the air.

> 2.  The NE/SW run will be running pretty evenly downhill and will drop from around 1150 feet to around 1000 feet above sea level.  While this is great for a Yagi, how will it affect the Beverage going downhill?  Conversely, how will the rise of 150 feet affect the Beverage in the opposite direction?

Mine are bi-directional and terminate into a rise in one direction, more 
or less flat in the other. Since I have no reference it's hard to say 
whether that matters.

> 3.  Finally, a 4 square will be used for transmit on 80, with the same drop.  Should I expect any enhancement  in the direction of the drop and conversely, any degradation in the uphill direction?  I think I know the answer to both questions, but want some opinions.  I can't model this on N6BV's HFTA so right now it's guesswork.

N6BT gave a talk at Pacificon two years ago documenting experimental 
work showing that a vertical very close to a drop-off had significant 
enhancement in the direction of the dropoff. As I recall, this was on 
20M. Slides are somewhere on the internet. Google is your friend. :)  As 
you probably know, the physics behind HFTA only applies to horizontal 
polarization.

73, Jim K9YC



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