The 5G Era is demanding better and more reliable communication systems. Microstrip antenna arrays operating in mmWaves play an important role in achieving the required performance, however they impose a great deal of design challenges. Besides, densely populated communication environments force those who design RF systems to miniaturize. The impact of reducing the distance between elements in microstrip antenna arrays is very noticeable in isolation. This work studies a method to maximize isolation in very compact antenna arrays. It consists of a direct 45° rotation of the radiating elements and the goal is to test whether it is possible to obtain similar isolation levels in very compact antenna arrays using this technique in comparison with the traditional patches’ layout and 0.5λ interelement spacing. This strategy presents a good compromise since it did not damage the antenna’s performance and it has improved isolation from 11.2 dB to 15.7 dB.