The polarity of a radio wave is controlled by the Electrical plane of the signal. For communications purposes, polarity allows for the reuse of frequencies to increase the total amount of transmission capacity on a satellite. By using one type of polarity to transmit to the satellite, and another to receive, the same signal may be used twice. Frequencies using different polarities do not interfere with each other.
LINEAR
Linear transmission means that a signal's broadcast geometry fits in a single plane. There are two types of linear broadcast for radio and microwave signals, horizontal and vertical.
- Horizontal propagation is parallel to the earth's surface.
- Vertical is perpendicular to the earth's surface.
CIRCULAR
Circular polarity is created by changing the signal polarity from horizontal to vertical in either a clockwise or counterclockwise direction.
- Right hand polarity is clockwise, and is also referred to as A-polarity.
- Left hand polarity is counter-clockwise and is also referred to as B-polarity.