RFID Tag Capable of Efficient Free-Space and Near-Metal Operation

Abstract The great majority of commercial UHF RFID tags are based on dipole antennas, and it is well-known that the tag performance,degrades significantly when,placed near a conducting surface. The question we address in this paper is: is it necessarily so? In this paper, we present evidence that suggest that it is not, at least to the degree that it has been observed. We present two antennas: one that performs optimally in free-space and performs 15 dB better near metal than a comparable,peer. The second antenna is nearly optimal near metal, but operates efficiently over a narrow frequency, and is “good” in free space. We present detailed simulated and measured,results for these two tags.