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Re: Topband: Beverage advice to bend or not?

Subject: Re: Topband: Beverage advice to bend or not?
From: Terry Conboy <>
Date: Sun, 16 Sep 2007 16:47:26 -0700
List-post: <>
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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