I've been playing with 2-el 80m wire beams and just tried
modeling a configuration with the elements at 70.6 & 60.4 feet.
The elements are inverted Vee-s with 120 degrees between the legs.
Spacing between the elements is 30 feet. The idea here is that the
elements are hung from a rope that goes from the top of the tower (72 ft)
to ground level 200 ft away from the tower.
What I found seems to be contrary to Tom's note about Force-12's
Zagi. That is, when I feed the lower element (using the upper one as
a director) the peak gain is 9.33 dBi (modeled over average earth with NEC-2).
But when I feed the higher one with the lower as the director, the
peak gain drops to 8.74 dBi. Take Off angle is about 45 degrees.
The other option is hang one element off each side of the tower. Looks
like then I can put both of the elements at 64 ft. In this case the peak
gain is 9.13 dBi.
Just curious to see if anyone else has noticed similar things from wire yagis
with elements at different heights.
Lee - KT4ZX
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Administrative requests: towertalk-REQUEST@contesting.com