Good analysis, Dave. Beverages depend on lossy soil underneath them to
work, and, as we all know, soil varies widely from place to place, and
even locally. I have very poor (rocky) soil, and the terrain under it in
my woods is quite irregular. For example, my EU/VK reversible Bev starts
at about 5 ft, running over the earth that drops gradually and then more
steeply to to a creek, losing about 30 ft of elevation, then climbing up
a steep rise to its termination point. Over that run, it's height above
ground varies from five feet to 10-12 feet. For most of its length, it's
held up by laying on top of brush.
As 160M super-op has often said, "any Beverage is better than no
Beverage." His run through terrain at least as irregular as mine, and
he's deep in a ravine!
I do, however, object to "RF ground," and so do authorities like N0AX
and K6WX.
73, Jim K9YC
On 8/31/2021 7:58 PM, David Gilbert wrote:
Since actual RF ground could be almost anywhere (and could be definitive
or graded) depending upon your soil, practically speaking the difference
between 12' and 10' is a meaningless distinction.
The height above actual ground will of course moderately affect the
input impedance, but you're not going to know what that is ahead of time
and to be rigorous you would want to adjust the terminating resistance
for a more or less constant impedance as a function of frequency ... and
then set the turns ratio of the coupling transformer to match.
Personally, I think being THAT rigorous isn't all that rational. Put
your wire at 12' and use whatever input transformer and termination you
already planned.
73,
Dave AB7E
On 8/31/2021 5:56 PM, RVZ via TowerTalk wrote:
Wondering if anyone has had good success with a Beverage mounted 12'
above ground? 12' is the minimum clearance I need to safely clear a
drive way. Please reply direct as I hope to install tomorrow.
Thanks in advance for your reply! 73, Dick- K9OMRLVZ@aol.com
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