> On Friday, September 23, 2016 7:47 PM, Rudy Bakalov via TowerTalk
> <towertalk@contesting.com> wrote:
> > Hi Tor,
> This is very informative.
> Quick question- why did you chose the to wire of your L to slope toward the
> tower instead of away, sloping towards the ground? Would you reduce the
> impact
> of the tower in the middle by pulling the top wires away from the tower?
>
> Rudy N2WQ From: RT Clay <rt_clay@bellsouth.net>
I could slope them out and up into the surrounding trees, but it would be
harder to make them identical in that case because the 4 support ropes are
going out into trees at different heights. Also some trees are too close and
would get in the way. But yes, my way should have more coupling to the central
tower. Sloping them down decreases the feedpoint Z. Here's a comparison of
several choices, all with a perfect ground, #12 wire. BTW there is nothing
special about the height I use (45.5 feet), that is set by my smallest
surrounding tree :).
1. straight vertical wire: R=36.0
2. N4OGW element: 45.5 feet vertical, then up to center tower: R=31.6
3. inverted L, 45.5 feet vertical: R=28.0
4. N4OGW element, with symmetric top wire (same slope as #2): R=27.8
5. N4OGW element, raised 10 feet (i.e. for elevated radials): R=27.5
When I measure R for each vertical with an antenna analyzer (with others
isolated from ground), I get 37.4, 36.5, 37.1, and 37.1. All are tuned at about
3.475 MHz and the minimum dumped power is somewhere around 3.550. I have 40-60
radials on each vertical of varying lengths.
Tor
N4OGW
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