The present invention relates to use of a smart antenna for a RF reader on
a Radio Frequency Identification (RFID) system to significantly increase
the operating range of the RFID system. The smart antenna can be an
adaptive antenna array. The smart antenna comprises a plurality of
antenna elements and, by combining the signals from multiple antenna
elements, significantly increases the received signal-to-noise ratio. In
a noise limited environment, combining the signals to maximize the
received signal-to-noise ratio can be based on the maximal ratio
combining (MRC) principle. To achieve the best signal quality, the
received signal from each antenna can be phase-shifted such that the
resultant signals from all antennas are in phase. In addition, the signal
from each antenna can be scaled in amplitude based on the square root of
its received signal-to-noise ratio.