In this episode you will learn about antenna polarization – what it is, how it works, why is it important, and what polarization is typical for WISP antennas.
One the important parameters of antennas is polarization. It is a natural property of any antenna. Polarization says in which plane the the fields of the transmitted signal are changing. Polarization is decided by the antenna designer that determines the EM fields orientation.
Most commonly, antennas have linear polarization, that means that the fields of the transmitted signal are changing in a line. Vast majority of antennas for WISP networks are linearly polarized.
Horizontal and Vertical polarizations are typical linear polarizations. Some antennas have slant or dual slant polarization. This means the fields are changing in plane rotated most commonly by 45 degrees compared to H or V polarization.
To achieve the best results antenna polarization must match. Horizontally polarized antenna communicates perfectly with equally polarized antenna on the other end of the link. As the rotation angle between antennas increases, the level of received signal decreases because of the physics of EM waves. This is why orthogonal polarization provides the isolation and creates additional communication channel.
In the real world, isolation between H and V polarizations is not perfect. Antennas with two polarizations have a parameter called cross-polarization isolation which tell us how well the H polarized antenna system and V polarized antenna system are separated. The bigger the isolation the better!
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0:00 Intro
0:22 H, V, Slant polarization
0:48 Polarization in practice
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