>From comments received re my question about elevated radials, I am now
up to date in understanding that the "elevated radials" being discussed
can mean either "totally elevated" or "sloping upward from ground
elevated". The latter is a new one for this old dog.
Christman's article in Compendium #5 deals with models of totally
elevated horizontal radials and totally grounded (buried) radials. I
must dig his March 1993 QST article out of my archives to see what he
says about radials angled upward from ground.
Regarding Tom W8JI's comments re his conversations with Roy Lewallen,
W7EL about NEC-2: when he designed EZNEC, Roy incorporated a
"high-accuracy" (NEC Sommerfeld) ground which he claims to be accurate
for low horizontal wires down to .005 wavelength high (about 2.7 feet on
160m).
I may be wrong, but I thought that NEC-4.1 was supposed to be accurate
for horizontal wires near, or in, ground. If so, Christman's comparison
of EZNEC vs NEC-4.1 with near-equal results for elevated radial systems
says that W7EL did something right when he designed EZNEC.
Regardless of modeling results, I remain to be convinced either way,
i.e., ~5dB gain or <2dB gain (as Christman's models show) when adding
buried radials. Note that the modeling results or for gain at the
optimum takeoff angle. Perhaps the 5dB figure is true for ground wave
(zero degree takeoff), which NEC models cannot show (they show zero
signal at zero degrees).--???
73, de Earl, K6SE
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