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Re: [TowerTalk] ground radial project

To: "'K2VI'" <>
Subject: Re: [TowerTalk] ground radial project
From: "Rod Ehrhart/DXE" <>
Date: Fri, 14 Jan 2011 11:54:19 -0500
List-post: <">>
Hi Tony,


I am glad to hear that you chose the DX Engineering Radial Plate, since it is 
the most cost effective longest lasting solution
available for immediate attachment of radials. 


As many folks know, the more radials you install the better, up to a break 
point of the cost in wire and effort versus the benefit
of overall relative gain. The length of ground radials is much less important. 
For the multi-band vertical, it would be great if all
of them could be 65 feet or more, but we know yours will be a maximum of 55 
feet long.


For most hams, the number of radials to install for a ground-mounted vertical 
antenna should be calculated from the amount of wire
that is available. That calculation has been written about here many times. 
However, the answer to your question about how many
radials to install will not be determined by how much wire you have, since you 
have much more than is required for excellent
performance of one multi-band vertical antenna system. 


The data published over the years indicates that the point where very small 
increases in overall relative gain, by adding more
radials, is reached somewhere between a total of 60 and up to over 100 radials. 
Adding more radials results in insignificant
increases in relative gain, unless the number of radials is doubled! Most 
Amateurs are very satisfied with 40 to 60 radials, but
some are very pleased with their results when installing 90 or more. Of course, 
the condition of the soil conductivity has a bearing
on a particular antenna system's overall relative gain result, but the 
threshold of practical cost and effort versus relative gain
is still reached at around the same point. You will get what you get in your 
location, but you decide the number of radials you are
willing to put in and how they are laid out. 


For any ground-mounted vertical installation, plan for all radials to be laid 
out evenly spaced and straight away from the Radial
Plate in all directions. For an smaller irregular lot where all radials cannot 
all be an optimal long length, each radial should
travel as far as it can. Many times I have used the phrase "fill the available 
space with straight, evenly spaced radials". Do not
tie into metal fences that collect noise. The most benefit from the radial 
system is achieved when each radial wire is straight and
they are all evenly spaced. So here is a way to figure out how to lay a lot of 
evenly spaced radials, regardless of their individual
lengths, and without trying to eyeball it.


Since your minimum radial length is 25 feet, establish a circle that has a 
radius (r) of 25 feet from the antenna mount. The
circumference (C) of that circle is (2)*(pi)*(r) or C =  (2)*(3.14)*(25 feet), 
which equals 157 feet. Now, if you have decided that
you will be installing 60 radials (N = 60), the spacing (S) between each radial 
on the circle is calculated as S = C / N  or S = 157
feet  / 60 radials = 2.6 feet or about 2 feet 7 inches between each radial on 
the circle. If you want to put in 90 radials, then it
would be 157 feet / 90 radials = 1.74 feet/radial, or a little less than 1 foot 
9 inches between each radial wire on the circle at
25 feet from the antenna mount.


Working this out in advance, you will not need to worry about how far apart the 
radials are where they end, or trying to eye-ball
their spacing. When filling an irregular area with radials, each one will have 
a different spacing where they end. By using this
measurement method, you will be able to make all of the radials evenly spaced, 
and as long as they can be, for maximum antenna
system performance.




Rod - WN8R

DX Engineering


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