  Due to the low impedance and high feeding currents, it is naturally
challenging to design super-directive antenna arrays that perfectly match the
feed line, and this becomes almost impossible as the number of elements
increases. In this paper, we assert that it is crucial to consider the
trade-off between directivity and overall efficiency (to achieve high realized
gain) before employing super-directive arrays in real-world applications. Given
this trade-off (high directivity and low mismatch for high realized gain), a
4-element dipole array (unit array) is optimized using the differential
evolution (DE) algorithm. Then, the performance of the unit array in subarray
configuration scenarios is analyzed. Finally, the obtained parameters are
verified using the CST full-wave simulation software. The results clearly
indicate that the proposed unit array is a strong candidate for dense array
applications, particularly in the context of massive multiple-input
multiple-output (MIMO), thanks to its notable high gain and efficiency.
