How does antenna height affect the azimuthal radiation pattern of a horizontal dipole HF antenna at elevation angles higher than about 45 degrees?
Why A horizontal dipole's classic figure-8 azimuthal pattern, with deep nulls off the wire ends, only really shows up at low elevation angles and when the antenna is well above ground. When the dipole is lower than about 1/2 wavelength, ground reflection dominates and most of the energy goes up at high angles, where the pattern fills in and is nearly the same in all compass directions. This is exactly the NVIS condition used for short-skip regional work on 80 and 40 meters.
Watch out The idea that end radiation is eliminated is backwards: a low dipole fills in the end nulls rather than deepening them, and height certainly does affect the pattern, so the no-effect choice is wrong too.
Low dipole = cloud burner: under 1/2 wavelength high it radiates straight up in all directions (NVIS).