5G, the next generation of wireless communications, is focusing on modern antenna technologies like massive MIMO, phased arrays and mm-wave band to obtain data rates up to 10 Gbps. In this paper, we have proposed a new 64 element, 8×8 phased series fed patch antenna array, for 28 GHz, mm-wave band 5G mobile base station antennas. The phased array steers its beam along the horizontal axis to provide the coverage to the users in different directions. The 8×8 array contains eight 8-element series fed arrays. The series fed array is designed in such a way that it shows a mixed standing wave and travelling wave behaviour. The initial seven elements of the series fed array show a standing wave behaviour, while the eighth element shows a travelling wave behaviour. It is due to the provision of the matched inset feeding, to effectively radiate the maximum power arriving at this element. The array is operating from 27.9 GHz to 28.4 GHz with a 500 MHz impedance bandwidth. The gain of the array is 24.25 dBi while the suppression of the side lobes is −14 dB. The half power beamwidth of the array is 11.5°. The beam steering is performed which shows a stable side lobe level. The array shows a stable array gain throughout the impedance bandwidth without any beam tilting due to the variations in the frequency. The simulations are performed using both CST Microwave Studio Suite 2015 and Ansys Electromagnetics Suite 17.0 simulation packages.