Hi Fritz,
> I'm planning to put up several beverages on a farm that has cattle grazing
> all over it. For obvious reasons gradually sloping the beverages to
> ground level at both ends would require quite a bit of extra fencing to
> keep the cows away from the wire.
I have a similar problem. There is no need to slope the wire, it does
not reduce the vertical pickup off the ends unless the slope
extends a very long distance. 10 feet of vertical drop is ten feet of
vertical drop.
For an example, consider the K9AY loop or the Pennant antenna.
They use a sloped side (or sides) and the sides behave like a short
vertical, despite being sloped.
The ends of my Beverages slope a few feet, but just for mechanical
reason to reduce leverage on the end posts. My wooden end-posts
are five feet high so they don't need to be back-guyed.
> beverage? At the terminating resistor end of the beverage, the resistor &
> capacitor would be 10ft off the ground and then the coax would go
> vertically 10 ft down to a ground rod. Similarly, at the feed point end
> of the beverage, the matching transformer and feed-line connection would
> be 10 ft off the ground.
I think you are seeing a capacitor isolating the ground so voltage
can be applied down the Beverage? At least that is what I recall in
my newer edition.
You can do anything you like with capacitors and shields, and you
will have exactly the same "vertical pick up " at the ends of the
antenna. Vertical pick-up will be exactly the same as a single
unshielded wire. If there was a way to shield a system for good
common-mode currents and not bad ones, and someone
discovered it, they would be rich!
> If the answer to the previous question is yes, then is there any problem
> with several beverages "sharing" the same "ground system", i.e., a single
> capacitor and 10ft length of RG-62, at the feed point end?
Beverages should never share a common ground. The common
ground is a path where the unused Beverages will "pump" the
ground system's finite resistance up-and-down with their signal,
and it will couple to the Beverage you are using. Another way of
looking at this the unused antennas become part of a radiating
ground system for the used antenna.
The ends of separate Beverages should always be kept at least a
few times the height plus several feet apart, and especially not
share the same ground system!
73, Tom W8JI
W8JI@contesting.com
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