A COMPACT DESIGN EIGHT ELEMENT MULTIPLE INPUT MULTIPLE OUTPUT MILLIMETER-WAVE ANTENNA

In this paper, a compact design eight element multiple input multiple output millimeter-wave antenna is proposed. This proposed MIMO mm-wave antenna consists of eight antipodal Vivaldi antennas. The operating band of this proposed MIMO mm-wave antenna covers a 20-40 GHz which is intended for millimeter band 28 and 38 GHz of 5G mobile communication application. The overall dimension of the proposed MIMO mm-wave antenna is 200 x100 x21.2 mm(3) and each antenna element has a size of 25 x8 x0.8 mm(3). The result shows that the return loss of the individual antenna element (S-11, S-22, ..., S-88) at 28 and 38 GHz frequencies are -13.986 and -18.938 dB. The mutual coupling (S-21, S-31, ..., S-68, S-78)of the proposed MIMO mm-wave antenna are valued in the range of -30.629 to -81.429 dB, it means that the proposed MIMO mm-wave antenna has a high isolation (> 14 dB) between antenna elements. The impedance bandwidth (return loss < -10 dB) is achieved in the range of the entire of the operating band (20-40 GHz). It has a good VSWR which are 1.5 and 1.2 for 28 and 38 GHz frequencies, respectively. The proposed MIMO mm-wave antenna has also shown a good envelope correlation coefficient (ECC) which is less than 0.3 (requirement). Particularly, the ECC values are correspondingly 0.00002173 at 28 GHz and 0.000000751 at 38 GHz. In addition, the obtained diversity gains are 9.96 dB at 28 GHz and 9.99 dB at 38 GHz. The proposed compact eight element MIMO mm-wave antenna has good characteristics.