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.

This article presents the design and implementation of a beam-steering antenna array using a 4 × 4 Butler matrix feed network (BMN) for 5G applications. The proposed antenna array can achieve a gain of 14 dBi and a steering range of (+16 • , −47 • , +46.5 • , −15.7 • ) to cover angular range extending from 45 • to 135 • . To achieve that, a simple, 4 × 4 Butler matrix etched on a single-layer microstrip structure is designed, optimized, and fabricated. The proposed design incorporates phase shifters, 3-dB couplers, and cross-over couplers. The proposed matrix is employed as a feeding network for 4-element wideband LPDA antenna array. The fabrication results of the feeding matrix and antenna array show very good agreement with the simulated results.

A circularly polarized high gain hybrid rectangular patch/horn antenna with chamfered corners is presented in this paper. The measured impedance bandwidth of the proposed design extends from 26.7 to 28.7 GHz. The suggested design antenna exhibits circular polarization propagation over the working band, which is achieved by introducing chamfered corner overlapped patch antennas surrounded by the truncated pyramidal horn. The main purpose of this horn is to enhance the overall gain without any deterioration of other antenna characteristics (more than 4 dB over the operating band when compared to the patch antenna). The maximum measured gain of the hybrid antenna is 10.9 dBi. The radiation patterns of the hybrid antenna show directive broadside radiation with stable performance over the whole frequency band. The suggested antenna is analyzed and designed applying both the numerical simulator (CSTMWS and HFSS).