Far field horizontal polarization component of a dipole antenna

Question

An infinitely thin dipole radiates an electromagnetic wave which in the far field  is vertically polarized, with zero horizontally polarized component. I am trying to understand what happens when the dipole is "fat", i.e. its width is a significant fraction of wavelength. I have been told by several supposed experts that the horizontally polarized component stays zero regardless of whether the dipole is thin or fat. However, they failed to either provide a source/reference supporting this statement or a convincing argument why it is true. Anyone has a pointer to the true story?

Kthaxt · Answer

You will still get vertically polarized fields if you are exciting the same mode. As the dipole gets fatter, you shift the higher order modes down frequency. So there are chances you'll resonate a higher order mode which would have horizontally polarized radiation depending on your frequency of operation.

Think of it in terms of your current pattern. In order to get a horizontal polarization, there must be some horizontal current pattern to create that phase difference. So long as your current pattern remains the same as the "dipole" pattern, you will still get the same polarization in the far field.

Uses of fat antennas include bowtie antennas, which are preferred for their bandwidth. MIMO antennas often exploit multiple modes which
 have different polarizations. Some of these work by exciting your metal cellphone case which can be thought of as a "fat dipole" depending on how it is excited.

Far field horizontal polarization component of a dipole antenna

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