Balluff BIS U Basishandbuch Seite 43

BIS U Basic Manual
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Reference Antennas and Antenna Parameters
4.6 Impedance All components must have the same real impedance to allow the transfer of power between the
processor unit and the antenna.
The BIS U system is designed for connecting system components (antenna and cable) with a
wave resistance or impedance of Z = 50 Ω.
Deviations in the impedance will result in maladjustment that may cause reflections or standing
waves. These deviations can significantly reduce the performance of the overall system.
4.7 Polarization
The field vector of electromagnetic waves into the surrounding environment is directional. The
alignment of the field vector or the direction of vibrations is described as wave polarization.
A distinction is made between linear and circular polarization, whereby antennas with the latter
characteristic are more important. This is because the field intensity value for circular polarized
waves is the same regardless of the spatial orientation.
The reception characteristics of most UHF data carriers are similar to those of a dipole antenna
due to their design. Transmitting antennas with circular polarization are used to ensure that the
data carriers function correctly whatever their position.
Figure 6:
With circular polarization, an additional distinction is made between circular polarization in a
counterclockwise and clockwise rotational direction. This characteristic is not important in a
predominant number of applications, since transponders usually have linearly polarized antenna
properties.
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Circular polarized wave
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