Recent Progress in Circularly Polarized Meta-antennas

The recent progress in circularly polarized (CP) meta-antennas is discussed. The following topics are described: beam steering for a bent meta-line array antenna, gain enhancement for a left-hand CP wave using a conducting patch printed within a meta-loop antenna, a technique for rejecting interference signals using a null field created within a meta-spiral antenna, and realization of a balanced gain for the left-and right-hand CP waves radiated from a meta-curl antenna.