28/38 GHZ DUAL-BAND YAGI-UDA ANTENNA WITH CORRUGATED RADIATOR AND ENHANCED REFLECTORS FOR 5G MIMO ANTENNA SYSTEMS

—A novel design of an enhanced Yagi-Uda antenna is introduced for dual-band operation at 28/38 GHz. The antenna is constructed by a corrugated dipole strip and a capacitively end-coupled extension strip as the driving element, two reflectors, and one director. Periodic parasitic elements are added in front of the reflectors to enhance the antenna gain and improve the impedance matching. The driving dipole is fed through a coplanar strip line, and in order to facilitate the experimental measurements using a coaxial feed line, a microstrip to coplanar strip (CPS) line transition is employed. A four-port MIMO antenna system is constructed using the proposed Yagi-Uda antenna arranged at the edges of the mobile handset. Numerical and experimental investigations are achieved to assess the performance of both the single-element antenna and the four-port MIMO antenna system. It is shown that the simulation results agree with the experimental measurements, and both show good performance of the single antenna as well as the MIMO antenna system. The bandwidths achieved around 28 GHz and 38 GHz are about 3.42 GHz and 1.45 GHz, respectively, using the microstrip feed line. Each antenna has a maximum gain of about 9 dB. The four antenna configuration shows radiation pattern diversity required for MIMO system. The envelope correlation coefficient (ECC) and diversity gain (DG) are calculated, and the results show that the proposed MIMO antenna system is suitable for the forthcoming 5G mobile communications.