Eddy,
I've been using a 85-foot high T-Top vertical with four
elevated radials (about 19 feet high) sloped up from the ground level
feed point, since the fall of 1994. This antenna is supported by a
wood pole for the radiator and with a pair of steel pipes for each of
the radials; however the outer pipes are 60 feet from the end of the
radial wires. I offer these answers based only on my observations/experience.
(A) Is it true that a couple of elevated radials are just as
effective as the "optimum" amount of buried ones...?
I very much doubt it. More than 2 elevated radials--perhaps so.
(B) What is the "ideal" number of elevated radials that one should use...?
I have heard that some say about eight.
(C) How many elevated radials are "just enough"...?
Probably my four. I wish I had eight!
(D) How high should these radials be...?
I believe higher is better--like most ground plane antennas.
(E) Would it be a requirement that I raise the feedpoints of my
"L's" to the same height as the elevated radials, or can I simply
leave the bases where they are now (at ground level) & simply slant
the radials upward with no effect upon performance...?
You can slant them up (gull wing) as I do. Mine are slanted
at about 45 degrees. I wish the slant was much more gradual, but it
wasn't possible. [Less interaction/cancellation with the radiating
part.] I think mine hurt the desired signal to a small(?)
degree. Some articles below indicate that performance can be affected.
(F) Is it OK to bend the elevated radials to fit property allotments...?
No experience here. I would guess it is largely a matter of degree.
(G) What is the desirable length of an elevated radial...?
According to an article by Al Christman [More on Elevated
Radials, QST, March 1993, page 72]: 1/4 wave plus the height of the
radial above ground. This is what I have used.
(H) Should any existing connections to real earth at the base of the
"L's" (i.e. a ground pipe) be completed severed with a system of
elevated radials...?
I firmly believe that elevated radials should never be grounded.
Here are the references I used in designing my antenna:
1. Arch Doty, CQ, April 1984, page 24. Mainly for his
bibliography which is extensive.
2. Al Christman, QST, August 1988, page 35; and the correction
notice in QST, October 1988, page 44.
3. Al Christman, IEEE Transactions on Broadcasting, Vol. 37. N0.
3. September 1991.
4. Al Christman, QST, March 1993, page 72.
5. Paul Pagel, QST, July 1991, page 49.
See these more recent articles also:
1. Don Nott, Radio Guide, August 2006, page 8. Refers to
experience with AM broadcast antennas.
2. Rudy Severns, N6LF. His excellent WWW
pages http://www.antennasbyn6lf.com/ especially his articles for
QEX on his Experiments No. 3 and No. 5.
Good luck and 73,
Charles Shaw - N5UL
Hobbs, NM
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Topband Reflector
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