Effect of metallic objects and liquid supplies on RFID links

Metallic objects and liquid supplies around a reader and/or tags may significantly affect the read range of RFID systems. Strong reflecting signals may be generated by the metallic and liquid surface. Depending on the phase of the reflected signal relative to that of the signal transmitted by the reader or reflected by the tag, the reflected signal may affect the signal strength constructively or destructively. Thus, in some situations the read range may be extended due to the reflection, and in other situations the read range may be significantly reduced. The most significant impact is achieved when the metallic objects and liquid supplies are relatively large and close to the reader and/or tag. It is advised that the RFID system is operated away from metallic material and liquid supplies. Multiple RFID antennas may achieve spatial diversity and improve the link reliability over an extended read range.