The MIMO cube-a compact MIMO antenna

In this paper, we suggest a multi-input multi-output (MIMO) cube antenna to be used in a wide angular spread environment like an indoor channel. Both space and polarization diversity has been used to constitute the MIMO cube where all the 12 edges consist of electrical dipole antennas. There exist 12 parallel orthogonal transmission links, also called eigenmodes. For a half-wavelength dipole, nine of the eigenmodes have a mean gain higher than the conventional single-input single-output (SISO) system; the highest mean gain is about 8.5 dB/cube, and the theoretical capacity is about 62.5 b/s/Hz for a signal-to-noise ratio (SNR) of 20 dB. The number of essentially active eigenmodes, which is about 11 for a side length of lambda/2, reduces to six for a very compact cube with a side length of lambda/20. With the latter side length, the theoretical capacity is about 34 b/s/Hz. The compact MIMO system promises to give high capacity in a rich scattering environment and may be used for high data rate communications like wireless local area network systems.