Near-field antenna for a radio frequency identification shelf in the uhf band

This study presents the design of a near-field reader and tag antenna in the ultra high frequency (UHF) band that can be used for various radio frequency identification (RFID) shelves. The tag antenna is designed by introducing an `S`-shaped slot into the circular patch, and the reader antenna is a rectangular slot array fed by microstrip lines. These UHF antennas operating in the near-field are more reliable in many RFID applications where the reading distance is not the major factor. The electric coupling concept between the reader and tag antenna is employed for near-field communication.