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 circle. The magnitude of the electric field vector is constant.

A circularly polarized wave may be resolved into two linearly polarized waves in phase quadrature 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.

See polarization for more information.

A previous version of this article came from Federal Standard 1037C and from MIL-STD-188