User's Manual

User Guide

WherePort III User Guide D948 Rev B

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3 MAGNETIC COMMUNICATION BASICS

The WherePort 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 an

excellent device for monitoring tagged assets

3.1 Magnetic Fields

The magnetic field of the WherePort extends nearly equally in all directions creating an

elliptical field (Figure 10). The field has a direction that is determined by the position of

the coil that creates it.

Figure 10 WherePort Field

The field extends in all directions around the WherePort. 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’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 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 signal decreases (Figure 11).

WherePort Coil

Field Lines