Metamaterial inspired LPDA MIMO array for upper band 5G applications

In this paper, an enhanced upper band 5G multiple-input multiple-output (MIMO) array is presented. The proposed array is based on a wide band LPDA antenna loaded with epsilon near zero (ENZ) index metamaterial. The metamaterial cells result in more than 3 dBi gain enhancement. In addition, multiples metamaterial cells arrangements are studied including straight, concave, and convex rows. The array covers a wideband of MMW frequencies extending from 26 up to 39 GHz. The LPDA antenna element design consists of alternating five arms printed on RO5880 substrate. All of the dipole arms are uniformly placed along parallel microstrip feeding transmission lines on both sides of the substrate. The main feeding line is placed over a partial ground plane at the backside of the substrate. The MIMO-LPDA array exhibits stable radiation characteristics over the operating band. A maximum realized gain of 11 dBi is achieved at 36 GHz for a single element radiator. In addition, essential MIMO performance indicators such as Envelope Correlation Coefficient (ECC), Diversity Gain (DG), and Channel Capacity Loss (CCL) are examined and determined to fulfill the needed standard of ECC, DG, and CCL. The fabricated prototypes of both the single antenna element and the MIMO array show very good agreement with simulated results.