Adaptive antenna arrays is one of the most promising solutions for interference suppression in the crowded spectrum environment of the wireless communication systems such as 5G and behind where they are efficiently capable to steer their main beams and nulls toward desired directions and interfering signals respectively.  However, some difficulties can be raised when it comes to practical implementation of these arrays such as a high complexity weighting network due to deployment a large number of the adaptive controllers which result in a low convergence speed. The main goal of this paper is to investigate various array weighting configurations to simplify the feeding network and at the same time reduce the convergence speed of the adaptive algorithm while maintaining a satisfactory array performance. Proposed configurations include regular adaptive subarray, partially adaptive array elements, and partially adaptive irregular subarray. These array weightings are performed directly during the adaptation process, which are different from any other existing techniques. Simulation results fully confirm the advantages and the effectiveness of the proposed array weighting configurations in terms of faster convergence speed, better interference suppression, and simpler weighting networks.

Nowadays, users require a very high data rate with more and more small compact designs of antennas. Past and current technologies have struggled to meet these significantly increasing demands, and they have not yet been able to meet these requirements. Using multiple-input multiple-output (MIMO) systems with arrays can achieve compact designs and high gain at high frequencies. As it is known, the fifth generation of antennas requires substrates with low loss tangent, so that losses at high frequency should be as eliminated as possible. In this paper, we used the previous concepts in designing a 5G MIMO antenna array with improved isolation thanks to a square split-ring resonator (SSRR). Unlike traditional designs, we positioned the CSRRs between the elements of the array like a plus sign (+) where each of the array elements are isolated by a unit cell to avoid the mutual coupling between the elements, which improved isolation in a way classical position (cascading manner) of CSRRs can't achieve. In this design, 2×2 MIMO antenna array is presented with Rogers RT 5880 substrate. The dimensions of the substrate are 28×18.8×0.508 mm3. The achieved frequency band is from 27.58 to 28.391 GHz. With this SSRR, a 40 dBi reduction in the mutual coupling between the two patch antennas is achieved. The attained gain is about 10.2 dBi, while the radiation efficiency is about 90 % at 28 GHz. Inset-feed is used for impedance matching with 50 ?? microstrip line for each patch. The design is appropriate for Gaussian indoor and outdoor environments.