Low-profile loop antenna with doubled gain for RFID application

In this paper, an original design of a low-profile loop antenna with increased directivity is proposed. Odd- and even-mode currents excitation in the loop allows providing two times higher gain than the gain of a single loop or dipole. The special design of a power dividing network in order to excite odd-and even-mode currents with the amplitude equality and 90° phase difference between modes is suggested. The antenna designed as a planar thin-film structure is intended for radio frequency identification systems application.