An integrated design consisting of a multiple-input-multiple-output (MIMO) antenna system for fourth generation applications and a planar connected array (PCA) for fifth generation applications is presented. The proposed design contains a 4-element printed-inverted-F antenna-based MIMO antenna system and a slot-based PCA. The antenna system is fabricated on a commercially available RO-4350 substrate with ${\rm \epsilon }_r$ ϵ r equal to 3.5. The dimensions of the board are 100 × 60 × 0.76 mm3 representing a typical smart phone backplane size. The antenna system covers 2.1 and 12.5 GHz frequency bands via its MIMO and PCA parts, respectively. The design is planar, low profile and compact in structure that is suitable for wireless handheld devices and mobile terminals. The PCA also serves as a defected ground structure at 2.1 GHz thus having two functions. Isolation is improved by at least 4 dB. The PCA consists of a 4 × 3 radiating slots fed via a corporate feed structure. The measured gain and efficiency values at the centre frequency are at least 3.4 dBi and 74%, respectively, for the MIMO antenna system and 8 dBi and 80% for the PCA. The envelope correlation coefficient did not exceed 0.2824 for all antennas showing good MIMO performance.