Roy, W7EL wrote:
"Which orientation would provide the "correct" answer?"

Maybe none.

We know what the correct answer is at the feedpoint. By trial and error
we can find the most stable and least critical placement for our test
lead. We can calibrate our voltage indicator with a sample at the
feedpoint under the conditions that prevail.

A test lead perpendicular to the balanced antenna suffers the least
interference. It`s subject to imperfections and it`s subject to
improvements to overcome the imperfections.

In AM broadcasting we get away with hanging a sampling loop on each
tower of a directional array to monitor both tower current and phase. It
works well enough.

Do you have a better idea than a diode probe to sample voltage at the
end of a dipole?

Best regards, Richard Harrison, KB5WZI