  In literature, it is often said that a uniform circular array (UCA) composed
of a sufficient number of radiating elements is able to generate a vortex wave
with arbitrary topological charge. While providing a very simple and intuitive
solution without the need for any synthesis method, the excitation of UCAs by
means of a progressive phase shift does not always guarantee that vortex waves
are correctly generated, since a major role is played by the symmetry and
radiation properties of each individual element which constitutes the array.
When the UCAs are employed in vortex communication links, these symmetry
properties strongly affect the orthogonality of the channel modes and,
therefore, the communication efficiency. In this work, the symmetry breaking
associated with the radiation of vortex waves by UCAs and its impact on the
mode orthogonality are explored in detail.
