Non-foster matching of an RFID antenna

Novel designs of radio-frequency identification (RFID) tag antennas with better matching characteristics to achieve extended range for passive tags are investigated in ultra-high frequency (UHF) band. A microstrip dipole antenna with or without an integrated negative impedance converter designed to cancel out the antenna's input capacitance at resonance frequency was designed, simulated, constructed and measured for implementation in RFID applications.