A Novel Nearfield Reader Antenna for UHF RFID Application

The nearfield antenna with well-distributed field is required in radio frequency identification (RFID) system. In this paper, a nearfield antenna, with planar quadrifilar spiral antenna and feeding network is presented. The proposed antenna exhibits uniform field distribution with maximum variation of 10dB for both E and H fields in simulation, and field difference between inside and outside the range of antenna is 30dB.