At 02:49 AM 2007-09-15, Neil Carr G0JHC wrote:
>I can get the 1st 460ft of a beverage in a straight line at 10ft height,
>then the remaining 125ft to get it to a preferred length of 585ft would
>have to be at a 45deg angle. My question is, should I cut the beverage at
>460ft (A none standard length) or "turn the 45 deg corner" with the other
>125ft for a 585ft recommended length?
I sent Neil a version of this with 5 pattern plots, so sorry if it is
a little cryptic. I was surprised that the pattern for the beverage
with the angled end section wasn't all that bad. If anyone is
interested, I can send them the original message off list.
~o ~oooo o~o ~o~~
I ran some quick plots with EZNEC over High/Accuracy ("average")
ground with four 100 foot radials at each end (elevated by 0.6 feet
with the radials NOT under horizontal wires); 500 ohm
termination. Forward gain at 20 degree elevation was used for the
RDF calculation.
With final 125 feet at 45 degrees, with 585 feet or about 1.09 wl
overall (RDF=8.83 dB):
Compare to having all 585 feet straight, about 1.09 wl (RDF=9.72):
460 feet straight only, about 0.86 wl overall (RDF=8.32):
As an alternative, consider 460 feet straight, then 70 feet at 45
degrees, about 0.99 wl overall (RDF=8.56 dB):
Compare to having 530 feet straight, about 0.99 wl (RDF=9.18 dB)
There is some degradation of the pattern when the last 125 feet of
the 585 feet is bent at 45 degrees, losing about 0.9 dB of RDF and
causing a 10 degree pattern skew. The RDF is still about 0.5 dB
better than the 460 foot version. The 530 foot (0.99 wavelength)
bent version has a 6 degree skew, but about 7 dB better F/B than the
460 foot version and a very slightly (0.24 dB) better RDF. Which is
better will depend on the location of your likely QRM/N sources.
I can supply EZNEC models or other pattern plots (elevation, etc.).
73, Terry N6RY
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