RFID Tag Antenna Design Based on an Improved Coupling Source Shape

An improved coupling source structure for radio frequency identification (RFID) tag antenna is proposed, which can not only achieve broadband operation, but can also easily carry out a complex conjugate impedance match between antenna and RFID chip. The impedance bandwidth of the proposed antenna is approximately 15% (842-985 MHz) with respect to the center frequency of 925 MHz and covers the entire UHF RFID frequency band. It is confirmed that this kind of antenna is suitable for all the different tag antennas' applications.