User's Manual

User Guide
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User Guide, WherePort IV D1300 REV A
© Copyright WhereNet, Corp. 2008 WhereNet Confidential
7.0 MAGNETIC COMMUNICATION BASICS
The WherePort IV signal is carried by a magnetic field. The field’s shape and size is determined by the
orientation of the coil and the power level. It is not possible to aim the field. One of the characteristics of
a magnetic field is that it drops off rapidly. This produces a well-defined, localized field. These
characteristics make the WherePort IV an excellent device for monitoring tagged assets
7.1. Magnetic Fields
The magnetic field of the WherePort IV extends nearly equally in all directions creating an elliptical field
(Figure 9). The field has a direction that is determined by the position of the coil that creates it.
Figure 9 WherePort IV Field
The field extends in all directions around the WherePort IV. The direction of the field is suggested by
the way the field lines are drawn from the coil.
The field is detected and the signal received by a coil in the WhereTag. The orientation of the WherePort
IV’s coil in relation to the orientation of the tag’s coil affects its ability to detect the signal. The optimum
orientation is when the WherePort IV coil and the WhereTag coil are parallel to each other. The worst
orientation is when the coils are perpendicular to each other. As the coils move from optimum to worst
the ability of the Tag to detect the WherePort IV signal decreases (Figure 10).
WherePort Coil
Field Lines