It's a fairly simple antenna. Yes, one radial is all you really "need,"
a couple more help improve efficiency and increase the BW. In the olden
daze [50's], we'd use 3 or 4 and cut them just a little different. Also
increased the BW, especially on 10, and in the later 50's, 10 was open
28000 - 29700, 24/7. It's really a very forgiving antenna. The
radials, with rope extensions are often used as guys as well. The droop
angle will affect the main lobe elevation somewhat, but I'll bet I could
do a blind "taste" test with you and you'd never really know the
difference. That angle is more often used to adjust the impedance at
the feed point.
Make that angle 90 deg and you have a vertical half-wave dipole
center-fed out of phase. Make the elements 1/2 wave each, mechanically
easy on 10 and even 15, and cophase feed them in the center, and you
have a Franklin vertical [see KFBK, one of the last ones I know of].
Very versatile basic design, works great, lasts a long time.
73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County
On 7/26/2020 3:38 PM, Rick NK7I wrote:
The reading I've done says only one radial is required; that the
'favoring' in the direction of the radial is not enough to be worried
about; that there is no cancellation from opposing (or just more)
radials. I have used a single radial ground plane and found this to
be true (at 6' over dirt on 80M). It favors a morning net 800 miles
away, yet worked DX in any other direction easily (then I moved to a
rotating dipole at 60' which beats it out). That ground plane easily
beat out a horizontal dipole I used before them all (fixed, in the
'wrong' angle because of tree location).
Both the radiator and radial are tuned (equally), but the angle of
difference from dipole to the traditional 90 deg ground plane will
cause the resistance to vary (roughly 72 ohms as a dipole, dropping to
~50 ohms when at 90 degrees), So if another angle is chosen (inverted
Y), to match a 50 ohm feedline (to have a 1:1 SWR), the element
lengths are adjusted equally until that match is made; altering the
resonance of the wires (maximum transfer of energy). And inverted Y
antenna would be between that 50-72 ohm range, still acceptably low
SWR to not mess with.
Which again, is not a significant variance, so put it up, try it out
and compare to other antennas. Wire is cheap enough to play with and
try things out.
Modeling will demonstrate the pattern and 'take off' angles quite
clearly; reality is often different because of local objects, ground
resistance, height...
Don't forget to add a common mode current choke at the feed.
73,
Rick NK7I
On 7/26/2020 11:57 AM, Don Wilhelm wrote:
Fred,
That would be correct if they are oriented at 180 degrees from each
other so as to cancel the horizontal radiation. Elevated radials
must be tuned to be effective, but only 2 are needed. How much tuning
will depend on the height above ground.
73,
Don W3FPR
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