Performance investigation of space diversity for a 28/38 GHz MIMO antenna (applicable to mm-wave mobile network)

A multiple-input-multiple-output (MIMO) dual-band antenna system consisting of two elements, each of which built up of circularly polarized slotted patch antenna for mm-wave band 5G wireless handheld and portable terminals is described. Space diversity is used to achieve a good independent channel fading in MIMO systems. In theoretical analysis of MIMO systems often assume that each antenna is isolated from the other elements. It has been shown that the antenna spacing has a significant effect on both near-field and far-field performance of each element in two independent working bands and should be optimized in millimeter wave compact dual-band MIMO arrays. However, the main problem is that an optimized distance for lower band may not be suitable for upper band and vice versa. If electromagnetic limitations and interactions of the antennas are ignored, the MIMO system performance may be underestimated or overestimated.