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G9B05
How does antenna height affect the azimuthal radiation pattern of a horizontal dipole HF antenna at elevation angles higher than about 45 degrees?
Pick an answer to check it.
Answer: C. If the antenna is less than 1/2 wavelength high, the azimuthal pattern is almost omnidirectional
A dipole less than 1/2 wavelength high sends much of its energy upward, and at high elevation angles the azimuthal pattern is almost omnidirectional. This is why low dipoles work well for NVIS.
Tip: Low dipole: high-angle radiation goes everywhere.