Design techniques for circularly polarized antennas using metamaterial structures

In this paper four multi-frequency circularly polarized antennas are proposed. The first one is a 4-ports self-diplexed multi-frequency RHCP-LHCP antenna. The second antenna is a single-feed short-circuited circular patch antenna filled with metamaterial structures to obtain a single port circularly polarization antenna. The two last antennas proposed are conventional microstrip patch antennas filled with metamaterial structures, with some modifications in order to achieve the desired circularly polarization using only one port. Finally, both, dual-feed and single-feed configurations are compared.