In electrodynamics, circular polarization of electromagnetic radiation is polarization such that the tip of the electric field vector at a fixed point in space describes a helix as the wave propagates. The magnitude of the electric field vector is constant.
A circularly polarized wave may be resolved into two linearly polarized waves, of equal amplitude, in phase quadrature and with their planes of polarization at right angles to each other.
Circular polarization may be referred to as "right-hand" or "left-hand," depending on the direction in which the electric field vector rotates.
The term "Circular Polarisation" is often used erroneously to describe mixed polarity signals used mostly in FM radio (87,5 to 108,0 MHz), where a vertical and a horizontal component are propagated simultaneously by a single or a combined array. This has the effect of producing greater penetration into buildings and difficult reception areas than a signal with just one plane of polarisation.
See polarization for more information.
A previous version of this article came from Federal Standard 1037C and from MIL-STD-188