When electromagnetic wave transmitted to free space. There are two components transmitted with the propagation affected by antenna radiation. These component are orthogonal with the propagation direction. These components called polarization The polarization of wave direction is defined by electrical field.
Fig.1. Characteristic of Polarization 
Based axial ratio (AR), there are three kinds of polarization, the axial ratio is the ratio of the major line and minor axes of the ellipse.
There are 3 kinds of polarization and the characteristic :
1. Linear polarization, when the AR value is unlimited ( ). In this case, the minor axis's value is 0.
2. Elliptical polarization, when the AR value is between 1 < AR <
3. Circular polarization, when the AR value is 1
Fig.2. Kind of Polarization
Increase the capacity of transmission can be realized with using dual polarization transmitted. These method possibility used for linear polarization and circular polarization. In particular, the following can be obtained:
- Two orthogonal circular polarization, which described as Right handed-Circular Polarization and Left handed-Circular Polarization (The direction of rotation is for an observer looking the direction of propagation)
- Two orthogonal polarization, which described as Vertical and Horizontal (relative to local reference)
 Marald Gerard, Bousquet Michael.2009.Satellite Communications Systems 5th Edition.Willey:Singapore
 Anonymous.2013.Kind of polarization http://www.photonics.byu.edu/images/pole.GIF. [Access Date: 24th May 2013]