In reference to radials, Steve wrote:
Some years ago I saw a study done by Bell Labs or RCA or similar in the
1930's or so in a broadcast engineering handbook that showed some help even
a
mile or so away depending on the frequency. I wish I could remember the
specifics - sorry. If anyone can help with some specifics, I'd appreciate
it.
Cheers,
Steve K7LXC
TOWER TECH
-0-
The seminal work on buried radials was done by AT&T Bell Labs, in the 30's,
at a site in Sussex County, NJ, and conducted by staff from the Whippany NJ
labs. It was reported in the Bell System Journal--which was in the Rutgers
University Engineering Library, at the time I was there. It was summarized
more than once in Broadcast Engineering.
They experimented with # of radials, size, length, and buried depth, and
used a constant power exciter and field strength meter to evaluate the
changes.
The work included excavation to observe soil strata, and I think to make
conductivity measurements, although I'm no longer sure about the latter,
since I don't remember any details.
It was their work which led the broadcast industry to settle for 120 quarter
wave radials of #10 wire, buried a few inches for stability. Remember that
the figure of
merit was groundwave field strength. They didn't make vertical field
measurements.
Beyond that, the passing of time and reporting of amateur antenna work, and
the
'discovery' of elevated radials have brought us to the knowledge and
discussion
we presently have, here. For an amateur, the compromise between physical
size and
cost and efficiency usually becomes limited by our resources, rather than
physics.
N2EA
Jim Jarvis, President
The Morse Group, LLC
We create high-performance organizations.
jimjarvis@themorsegroup.net
www.themorsegroup.net
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|