Anonymous wrote:
"Of all the HF antennas one might reasonably make out of wire or
aluminum tubing, which produces the strongest groundwave?"

Vertical antennas make the strongest groundwaves.

Assuming you are confined to a single ground-mounted element of
reasonable height and complexity, Kraus in the 3rd edition of "Antennas"
gives a simple answer in Figure 16-35 on page 569. A 0.64-wavelength
tall vertical radiator produces the greatest field strength at one mile
in the direction of the horizon.

Best regards, Richard Harrison, KB5WZI

"Richard Harrison" wrote
Kraus in the 3rd edition of "Antennas" gives a simple answer
in Figure 16-35 on page 569. A 0.64-wavelength tall vertical
radiator produces the greatest field strength at one mile
in the direction of the horizon.
_____________

....and subparts (c) and (e) of that figure clearly show the high-angle
sidelobe centered at about 58 degrees elevation from an 0.64-lambda monopole
that may cause self interference -- per Roy Lewallen's post earlier in this
thread.

RF

Eichard Fry wrote:
"...and subparts (c) and (e) of that figure clearly show the high-angle
sidelobe cebtered at about 58 degrees elevation from an 0,64-lambda
monopole that may cause self interference..per Roy Lewallen`s post
earlier in this thread."

All too true. In AM broadcasting, at night the sky wave may interfere
with the ground wave beyond the skip zone.

In HF transmissions, the ground wave is likely exhausted in short order
so that the sky wave is the only signal available at considerable
distances. There will be no ground wave to beat with the sky wave to
cause fading but there are numerous paths for the sky wave which produce
plenty of fading without adding any ground wave to the mix.

Best regards, Richard Harrison, KB5WZI