Topband: Radial Wire System Comparison - (was adding a parasitic reflector to a vertical)

[Paul Christensen]

Dan and all...

I am in the middle of constructing 4-squares for 160m and 80m.  One element
of each array is up and operating.  A decision must be made concerning the
layout of Teflon-insulated radial wire and whether to run a bus wire/strap
at the intersection of overlapping radials.  It may not seem like it, but
it's a lot of extra work and I just want to ensure the effort is worth the
result.  Cost of the extra wire is not the issue.  

What I am trying to determine is how much detrimental wire-to-wire coupling
occurs when *insulated* radial wire cross and its effect on: (1)
cancellation of radial current; (2) pattern; and (3) F/B performance.  I
have researched Laport's material, and find nothing that compares
multi-tower array performance when using insulated radial wire versus
uninsulated wire when using a bus wire at the radial overlap points.  Since
his worked in the 1950s mostly focused on directional broadcast tower arrays
-- and the use of heavy-gauge wire, possibly insulated radial wire wasn't
considered because of long-term insulation decomposition that one day
results in electrical contact between overlapping radials.

So, can anyone point me to results that show a modeled comparison between
the two types of radial system layouts and even better, actual measured
field strength results?  I do have a NEC 4.2 license, 4Nec2, and just
recently purchased EZNEC Pro/4 and AutoEZ.  Ultimately, I will run my own
analysis, but it always helps to look at someone else's data to ensure
ground system modeling is set up correctly.

Paul, W9AC


-----Original Message-----
From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of Dan
Maguire via Topband
Sent: Thursday, February 1, 2018 2:02 AM
To: topband at contesting.com
Subject: Re: Topband: Adding a parasitic reflector to a vertical

For AutoEZ users:  A model similar to the parasitic array that Tim described
is available on this page:

http://ac6la.com/aecollection8.html

In the first section of that page, scroll down to topic "Parasitic Elements"
and then look for the text "For a vertical parasitic example I chose a model
described by N6LF ...".  The sample model is for 80m but everything is
controlled via variables and there are instructions (within the model
itself) on how to scale for other bands.

Links to several references are also included on the above page.

Dan, AC6LA
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