A Dual-Band Metamaterial Superstrate for Antenna Gain Enhancement

This paper presents the design of a dual-band anisotropic zero-index metamaterial (ZIM)superstrate which can be used with antennas to enhance their gain in two frequency bands. The unit cell of proposed design consists of two capacitively loaded loops (CLL)which are nested to achieve dual-band operation. The extracted parameters of the resulting periodic structure show that permeability of the metamaterial is close to zero at 2.4 GHz and 3.5 GHz respectively. Used as a superstrate to a printed monopole antenna, the ZIM enhances its gain by 2.8 dB and 3.8 dB at 2.4 GHz and 3.5 GHz.