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BIS U Basic Manual
8
Reflection, Dispersion and Adsorption of Electromagnetic Waves
8.1 Changes in the
Polarizing Axis
Ratio
8.2 Effect of Different
Environmental
Conditions
22
Interaction with structures in the surrounding area changes the axis components of a circular
polarized wave, which are originally almost identical in size.
These changes result in noticeable differences in the reading performance or reading range
depending on the degree of response field intensity and on whether the data carrier is mounted
in a vertical or horizontal position.
8
7
6
5
4
3
2
Horizontal component
1
0
0
50
100
Figure 13:
Changes in the axial ratio of polarization components
The positioning, materials and geometry of the obstacles in the surrounding environment can
vary from application to application and can therefore be expected to have a direct effect on the
appearance of the electric field distribution. In Figure 14, the vertical component of the electrical
field intensity curve has been measured comparatively for three different spaces in the main
propagation direction using a circular polarized antenna.
8,00
7,00
6,00
5,00
4,00
3,00
2,00
1,00
0,00
0
100
Figure 14:
Free space loss curve for three different spaces in main dispersion direction
Vertical component
150
200
250
Distance to the antenna in cm
Free space loss - vertical component
______
______
______
200
300
400
Distance to the antenna in cm
300
350
400
Space I
Space II
Space III
500
600
450
700
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