Polarization of the field radiated by the antenna is another important specification. Polarization refers to the path traced by the tip of the electric field vector as a function of time. There are three forms of polarization: linear, circular and elliptic.
Linear polarization occurs either when there is only one component of the electric field or when there are two components of the electric field and the phase difference between them is 0° or 180°. The pattern traced by the tip of the electric field vector as time progresses is a line. Circular polarization occurs when there are two components of the electric field, and they are equal in magnitude and one of the components leads the other by 90°. Circular polarization can be either right handed or left handed, depending on the direction in which the rotation of the field occurs with time. Elliptical polarization occurs when the components of the electric field do not have the same magnitude and have an arbitrary phase difference between them; the electric field vector traces out an ellipse with time.
The figure illustrates the different types of polarization of the electric field radiated by an antenna.