Isolation improvement of two-port multiple-input-multiple-output antenna using slits and split ring resonators on the ground plane

In this paper, a multiple-input-multiple-output (MIMO) for dual frequency band is proposed. Each antenna consists of two folded planar inverted F structure with slits and split ring resonator (SRR) cells on a ground plane. It is designed on a FR-4 substrate (relative permittivity = 4.4, height = 0.8 mm) using micro-strip technology. The size of the ground plane and each chip type planar inverted F antenna (PIFA) is 50 mm × 100 mm and 35 mm × 5 mm, respectively. For the isolation improvement between two antennas, a quarter-wavelength open slit is designed for long term evolution (LTE) band and five SRR cells is designed for united state personal communication services (USPCS) band. The measured isolation between two antennas has been enhanced to be near -20 dB by using slits and SRR cells on the ground plane.