Planar two-element UWB MIMO antennas with high isolations

Two compact planar UWB MIMO antennas for wireless communications are presented. The first antenna, which operates in the 2.3-12 GHz frequency band, has a size of 72 mm × 48 mm × 0.76 mm. High port-to-port isolation over the whole ultra-wideband is achieved by using an inverted-T stub between the elements. The second antenna has a size of 34 mm × 47 mm × 1.6 mm, and operates in the band from 3.8 to 11.8 GHz. Unlike other designs, the radiators are reversely parallel placed for achieving high isolation between two ports. Furthermore, an interdigital-like structure, which is composed of stubs and strips, has been employed to enhance both the isolation and the bandwidth. The current distributions, S parameters and radiation patterns of both antennas are given. The results show that, both antennas have high isolation of more than 20 dB over the ultra-wide operation bandwidth. The proposed antennas are suitable for some portable MEVIO/diversity applications.