Electromagnetic waves propagate in space unipolarized, they have no fixed plane of oscillation. It is only through polarisation
that a specific plane of oscillation is defined. Polarization can be horizontal, vertical or in other planes, but it is also possible to influence polarization so that the wave propagates
inspace in a circular manner. In this context, one speaks of circular polarization, which can be generated with helical antennas
. Depending on whether theelectromagnetic wave rotates clockwise or counterclockwise when viewed from the helical antenna, it is referred to as right-hand circular polarization
(RHCP) or left-hand circular polarization (LHCP). Circular polarization is realized by antennas whose antenna elements are at right angles to each other and which also radiate two transmission signals that are 90° out of phase.