What is Antenna Polarization and Its Types

• Polarization is defined as the special property of electromagnetic waves that provides a specific relation between the time-varying direction and magnitude of the vibrating electric field.
• Polarization of an antenna is loosely defined as the direction of the electromagnetic fields produced by the antenna as energy radiates away from it.
• These directional fields determine the direction in which the energy moves away from or is received by an antenna.

Types of Polarization

1. Linear Polarization
2. Circular Polarization
3. Elliptical Polarization

1.  Linear Polarization

• A type of polarization in which all the waves possess similar alignment in space either vertical or horizontal is known as linear polarization.

a) Vertical polarization-

• It is the linear polarization in which the wave travels perpendicular to the surface of the Earth.

b)Horizontal Polarization-

• The linear polarization in which the wave travels horizontally to the surface of the earth.

c) Slant Polarization-

• In a slant polarization antenna, rather than horizontal and vertical, the polarization is at –45 degrees and +45 degrees from a reference plane of 0 degrees(surface of the earth).

2. Circular Polarization

• Circular polarization of an electromagnetic wave is a polarization state in which, at each point, the electromagnetic field of the wave has a constant magnitude and is rotating at a constant rate in a plane perpendicular to the direction of the wave.
• It occurs when the two orthogonal electric field component vectors are of equal magnitude and are out of phase by exactly 90° or one-quarter wavelength.

1) Right-hand Circular Polarization-

• In this form of polarization, the vector rotates in a right-handed fashion.

2) Left-hand Circular Polarization-

• In this form of polarization, the vector rotates in a left-handed fashion, i.e. opposite to right-handed.

3. Elliptical Polarization

• When two linearly polarized waves of unequal amplitudes that are mutually perpendicular to each other are combined then the elliptically polarized wave is produced.

Co-Polarization and Cross-Polarization:

• Co-polar means when the polarization of both the transmitting (test antenna) and receiving antenna (reference horn antenna) is the same.
• Cross polarization means when the polarization of both antennas is different.