Dual-band circularly polarized hybrid metamaterial patch antenna

In this paper, a small dual-band circularly polarized (CP) hybrid metamaterial (HMTM) patch antenna is presented by utilizing the first positive (+1) mode and the first negative (-1) mode. The -1 mode is generated on the periodic mushroom structures that provide a left-handed (LH) property of the metamaterial (MTM). Similarly, the CP radiation can be also obtained by using two orthogonal -1 modes, because the -1 mode has the same property with the +1 mode. To obtain two +1 modes and two -1 modes simultaneously, the trimmed patch antenna and 2 × 2 mushroom antenna are employed, respectively, and two antennas are united into one. It is measured that the CP radiations of the +1 and -1 modes appear 2.846 GHz ~ 2.887 GHz and 3.829 GHz ~ 3.835 GHz, respectively. Finally, the radiation efficiencies are measured to be 87 % and 47 % of the +1 mode and -1 mode, respectively.