Dual-Band Circularly Polarized Crossed-Dipole Antenna Backed by a Double Layer Artificial Magnetic Conductor

In this paper, a dual-band, circularly polarized (CP) and unidirectional radiative antenna is designed for ISM 2.45/5.8-GHz applications. Two crossed printed dipoles are employed to form the radiation elements of the antenna, which obtained the CP radiation by using a vacant-quarter ring. Each dipole arm is divided into two branches with unequal lengths, and a meander line is inserted into the longer branch to minish its size. A double layer artificial magnetic conductor (AMC) is designed as a reflector to achieve the unidirectional radiation, which exhibits a better performance than traditional single layer AMC. The simulation results show that the -10-dB impedance bandwidths are 2.2-2.6GHz (400MHz), 5.1-6.3GHz (1200MHz) and the 3-dB axial-ratio bandwidths are 2.31-2.56GHz (250MHz), 5.44-6GHz (560MHz) respectively, which absolutely cover the ISM 2.45/5.8-GHz frequency band.