This work presents an antenna system with integrated approach for 4G LTE and high frequency (mmwave) 5G communication systems. The proposed antenna solution comprises of two-element antenna array module for sub-6 GHz 4G bands, and MIMO antenna system resonating at 5G mm-wave frequency band. The array elements are excited by a feed network based on the T-junction power divider or combiner. The proposed design has overall dimensions of 135×77×1.575 mm3. The 4G antenna module is placed at the top side of the board, while the four 5G MIMO antennas are loaded on the longer edges of the board. The 4G band obtained is ranging from 2.2-4.9 GHz. Whereas, the 5G antennas cover the 26-28.8 GHz band, which is a potential band for future 5G wireless applications. Moreover, the peak gain obtained by the 4G antenna module is 7.31 dB while 9.21 dB by 5G antennas. In addition, the MIMO performance of the proposed 5G antennas is also investigated. Hence, the simple structure, compactness, and performance of the proposed design ascertain it to be suitable for existing and forthcoming handheld devices.