On Aug 6, 8:06 am, "Richard Fry" wrote:


A NEC-2 model of a 1/4-wave vertical monopole (base at earth level) in the
AM broadcast band using just four, 1/4-wave radials elevated 12-15 feet
above a perfect earth shows a peak h-plane gain within tenths of a decibel
of the theoretical peak value for a 1/4-wave monopole over a perfect ground
plane, ie, at least 5 dBi.


Dunno. I'll have to ponder that a while.. But something doesn't seem
right to
me.. My red flag is going off.. By "perfect ground plane", I assume
you mean
120 radials? I have a hard time seeing 4 low elevated radials within 1
db
of 120 buried radials over real ground. I realize the ratio should be
equal
if converted to "perfect ground" but still, this just doesn't seem
right to me.
I know I've never seen results like that here on real earth. I've
tried four
slightly elevated radials quite a few times on 160m, and I've never
had the
illusion of performance nearly equaling 120 on the ground.
In fact, I've heard of a few others that complained how lousy that
type
of system worked overall, and went to many more buried radials with
better results.
Lets say the two were over poor earth. I would think the 120 radial
system would still be pretty low loss, but the 4 radial system quite
stunted
in comparison. I have a hard time seeing them within a few tenths of a
db
of each other. I dunno if I trust that particular modeling... :/
MK