Ultra-wideband (UWB) RFID systems offer the highest resolution. These systems can usually pinpoint a tagged item to within about 10 inches in three dimensions. This is largely due to the fact that UWB systems do not have the same issues with multipath distortions that other RFID systems often have. Multipath is when a tag signal bounces of ceilings, floors, walls and objects before being received by an interrogator. These signal reflections make it difficult to determine a tag’s precise location.
There are passive ultrahigh-frequency (UHF) real-time location systems (RTLS) that can also locate an object in three dimensions, usually to within approximately three feet. Most other systems do not provide 3D positioning.
—Mark Roberti, Editor, RFID Journal
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