Common polarization methods of antennas

　　1. The direction of the electromagnetic field radiated by the antenna is the polarization direction of the antenna.

　　2. Dual polarization antenna

　　(1) Two antennas form a whole

　　(2) Two independent waves

　　3. Circularly polarized wave

　　If the direction of the electric field during the propagation of a radio wave is rotating, it is called an elliptical polarized wave. During the rotation process, if the amplitude or magnitude of the electric field remains constant, we call it a circularly polarized wave. A clockwise rotation in the direction of propagation is called a right-handed circularly polarized wave, while a counterclockwise rotation is called a left-handed circularly polarized wave.

　　Vertical polarized waves should be received using antennas with vertical polarization characteristics; Horizontal polarization waves should be received using antennas with horizontal polarization characteristics;

　　A right-handed circularly polarized wave should be received using an antenna with right-handed circularly polarized characteristics; And left-handed circularly polarized waves need to be received using antennas with left-handed circularly polarized characteristics. When the polarization direction of the incoming wave is inconsistent with the polarization direction of the receiving antenna, polarization loss is usually generated during the receiving process. For example, when receiving any linearly polarized wave with a circularly polarized antenna, or when receiving any circularly polarized wave with a linearly polarized antenna, a polarization loss of 3 decibels is generated, that is, only half of the energy of the incoming wave can be received;

　　4. Polarization loss

　　When the polarization direction of the incoming wave is inconsistent with the polarization direction of the receiving antenna, polarization loss is usually generated during the receiving process. For example, when receiving any linearly polarized wave with a circularly polarized antenna, or when receiving any circularly polarized wave with a linearly polarized antenna, a polarization loss of 3 decibels is generated, that is, only half of the energy of the incoming wave can be received;

　　When the polarization direction of the receiving antenna (such as horizontal or right-handed circular polarization) is completely orthogonal to the polarization direction of the incoming wave (corresponding to vertical or left-handed circular polarization), the receiving antenna cannot receive the energy of the incoming wave at all. In this case, the polarization of the incoming wave and the receiving antenna is said to be isolated.

　　5. Isolation degree

　　Isolation represents the proportion of signals fed to one polarization appearing in another polarization.

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