User's Manual

25
Signal Attenuation/Reflections
Signal attenuation is the loss of signal strength that occurs naturally
over distances, but which can also be caused by RF barriers in the
signal path.
Examples of such barriers include:
• Enclosed locations that have concrete walls, floors, and ceilings.
• Metal surfaces surrounding the antenna or tag.
• Water or other fluids surrounding the antenna or tag.
Almost every object (furniture, partitions, and people) in the path of a
signal causes some degree of attenuation. The effects can be minimized
by careful antenna placement.
The reflection from metal or metallic surfaces behind the tag can also
affect signal attenuation. In some cases, this may increase the read
distance slightly, while inducing intermittent “dead” spots within the read
field that permit little or no communication between the scanner and
tag.
556-EP Manual.P65 1/18/2001, 2:46 PM25