[TowerTalk] 80 meter vertical

[jimlux]

On 1/19/19 6:58 PM, john at kk9a.com wrote:
> That is a great question, I have wondered this many times when operating on
> the sloping terrain in VP2V and KP2. To my knowledge there is no modeling
> software that will show a vertical's pattern on a hill.

No readily available amateur radio software..I'm sure that there are 
codes out there.. Maybe HFSS could do it, but I'm not sure it's well 
suited to this.

If it is a "uniformly sloping hill", you could put a vertical that 
slopes at the hill angle into NEC and model with flat earth. - then 
rotate the pattern you calculated.


But once you get away from that, it's trickier. You can do a fairly 
straightforward raytrace for H pol, the reflection coefficient varies 
smoothly and is generally large, and the usual assumption is that the 
soil surface is parallel to the polarization.
V pol reflection coefficient varies a lot, and you need to deal with 
things like diffraction.



> 
> John KK9A
> 
> Tom Osborne w7why wrote:
> Hi All
> 
> I have tried putting  up an 80 meter vertical 3 or 4 times.  No matter what
> I do, it is never better than my twinlead fed 80 meter dipole up about 65
> feet.. This is both on close in stuff and longer range propagation.
> 
> I tried it with the radials on the ground, with the feed point elevated
> about 6 - 8 feet with 4 raised radials, and about every combination I can
> think of.
> 
> I was wondering if living on the side of a 450 foot hill makes a
> difference?  The hill slopes down to the bay below my house.
> 
> I have a 20 meter HB beam up about 25 feet.  f I walk to the east about 25
> feet, and look back, the 20 meter antenna looks like it is about 60 feet
> up.  Goes higher as I walk farther east down the hill.
> 
> Do verticals work poorly on the side of a hill, or does it make any
> difference at all??  Thanks and 73
> 
> *Tom W7WHY*
> 
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