What happens when antenna dual polarization is generated?
A dual-polarized antenna radiates (or receives) two waves with
polarizations that are orthogonal (perpendicular) to each other in space.
Polarization Loss
Vertically polarized waves should be received with an antenna with vertical
polarization characteristics, while horizontally polarized waves should be
received with an antenna with horizontal polarization characteristics.
Right-hand circularly polarized waves should be received with an antenna with
right-hand circular polarization characteristics, while left-hand circularly
polarized waves should be received with an antenna with left-hand circular
polarization characteristics.
When the polarization direction of the incoming wave does not match the
polarization direction of the receiving antenna, the received signal is
weakened, which is called polarization loss. For example, polarization loss
occurs when a +45° polarized antenna receives vertically or horizontally
polarized waves, or when a vertically polarized antenna receives +45° or -45°
polarized waves. When a circularly polarized antenna receives any linearly
polarized wave, or vice versa, polarization loss inevitably occurs—only half of
the incoming wave's energy is received.
When the receiving antenna's polarization direction is completely
orthogonal to the incoming wave's polarization direction, for example, when a
horizontally polarized antenna receives a vertically polarized wave, or when a
right-handed circularly polarized antenna receives a left-handed circularly
polarized wave, the antenna receives no incoming wave energy at all. In this
case, polarization loss is maximized, and this is called complete polarization
isolation.
Polarization Isolation
Perfect polarization isolation does not exist. A small amount of signal fed
into an antenna with one polarization will always appear in an antenna with the
other polarization. For example, in the dual-polarized antenna shown in the
figure below, if the input power into the vertically polarized antenna is 10W,
the output power measured at the output of the horizontally polarized antenna is
10mW. Electronic antenna manufacturers think: Don't underestimate the magnetic
field, because it is not just a simple magnetic field. Everyone knows that if
the magnetic field is relatively large, unexpected things will occur.
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