Polarization can be horizontal, vertical or in other directions. However, it is also possible to influence the polarization in such a way that the wave propagation in space is circular. In this context it is called circular polarization.
In circular polarization, which is produced by helical antennas, the field strength vector, which is perpendicular to the direction of propagation, turns right or left. Depending on whether the electromagnetic 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 generated by two antennas whose antenna elements are at right angles to each other and which are driven by two transmit signals that are 90° out of phase. With circular polarization, atmospheric interference can be suppressed.