Grant, that is very interesting results. I could certainly break up all
the strands with strain insulators, the nice strong porcelain ones, and
even at 150 or 100 ft intervals if the results would warrant. The bad
news is I'm afraid my fences are not pointed at much desirable
activity. (Boo Hoo!). I could temporarily string a Beverage E-W and
see what it hears. Then if I like what I hear I could break up a
section of with insulators and hang a wire above it as a more permanent
fixture.
Thanks again for your contribution. I wish I would have thought of
breaking the fence up with insulators. Well du-uh!
Patrick NJ5G
On 2/3/2015 4:11 PM, Grant Saviers wrote:
I did a quick EZNEC Pro/4 analysis of a Beverage over a 3 strand barb
wire fence, strands at 4,3,2' and antenna at 10'. I've had one that
sorta worked, now I know why.
600' of fence under 600' of antenna yields a substantially degraded
F/B (what I experienced).
2400' of fence under 600' of antenna yields a substantially vertical
pattern
Insulator breaks of the 600' of the 3 strands every 200' yielded a
1.8Mhz pattern almost the same as no fence. Adding a single strand of
continuous single fence out 600 to 1200' past both ends of the
Beverage had minimal pattern change. At 3.5 and 7 Mhz the pattern
looses a bit of F/B but is tolerable IMO.
So for a few insulators, a Beverage works over a barb wire fence.
Porcelain eggs would probably be the best bet for the strength needed.
Chain link and welded mesh fences are best avoided unless it is worth
the work to insulate sections.
Grant KZ1W
On 2/3/2015 12:52 PM, Joe Subich, W4TV wrote:
Pat,
8 to 10 feet above the barbed wire fence would be your only chance if
you are to use the existing fence lines. I would strongly suggest
reading some (all) of the references you have been offered -
particularly those that include long term experiments.
My information has simply been gathered from the reports of others over
nearly 40 years and confirmed by the performance of the few simple
Beverages I've been fortunate enough to use at various times.
The general consensus has been not to use a "ground wire" under a
Beverage or run it along above/parallel to a conductive wire fence.
Maintain at least 45 degrees and try, if at all possible, to cross
other antennas/conductive objects at right angles.
snip...
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|