Capacitively-loaded Inductively-coupled Fed Loop Antenna with an Omnidirectional Radiation Pattern for UHF RFID Tags.

A capacitively-loaded inductively-coupled fed loop RFID tag antenna with an omnidirectional radiation pattern is proposed. With an inductively-coupled feed structure, it is convenient and accurate to achieve conjugate impedance matching condition. Concentration of surface current on the radiating loop is beneficial to improving the gain of antenna. The radiation pattern which is omnidirectional in antenna plane makes the proposed tag practicable mounted on top or bottom of target objects. The length of the antenna is only 60 mm, and the maximum simulated read range of the prototype is 14 m with 4 W of EIRP. [ABSTRACT FROM AUTHOR]