Topband: Radial system gain
w8ji at contesting.com
Fri Sep 29 15:35:41 EDT 2006
Anyone wanting to see actual measurements of radial systems
needn't look very far.
You can download Brown, Lewis, and Epstein's data from
If you go to page 12 and look at figure 30 you'll find the
following was documented:
1.) An absolute perfect zero loss ground system (available
only in theory) and a 1/4 wave vertical produces a field
strength of about 196mV/m at one mile with one kilowatt.
That's zero elevation angle, so we are looking at low wave
2.) B,L, and E using reliable measurements on 3MHz obtained
192uV/m with 113 radials about 1/2 wl long. That's 0.4dB
below a perfect conductivity sheet.
3.) 60 radials under the same conditions produced about
185uV/m. That's 0.5dB below a perfect sheet. One tenth dB is
gained by almost doubling the radials to 113, and the
ceiling if we made the ground a solid zero loss sheet of
superconductor would be a whopping 1/2 dB better.
That was for 1/2 wave radials.
Now if we look at page 12 figure 31, we see measurements for
approximately 1/4 wave long radials.
1.) Again an absolutely perfect lossless system would
provide about 196mV/m with a kilowatt and a quarter wave
2.) 113 radials they measured about 180mV/m or 0.74dB below
3.) 60 radials they measured about 175mV/m or 0.98dB below
perfect. The difference between 113 radials and 60 radials
about 1/4 wave long was only 0.24 dB.
We can make whatever excuses we like, but there are multiple
sources of actual measurements that show we will have less
than 1dB gain with a vertical going from 50 or 60 radials to
a perfect zero loss sheet with a zero loss radiator. The
shooter the vertical, the more important the ground becomes.
N6LF posted a link to FS measurements at
Those measurements reasonably agreed with measurements I've
made and that others have made over the years.
I have a ~200 foot tall vertical with 100 radials at least
200 feet long, and it is consistently about 5-7dB worse than
my four square. I wish I could get another 6 or 10dB,
especially while Omni. There just isn't any magic.
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