Compact wideband MIMO antenna with fragmented patches for 5G mobile terminals

A compact wideband MIMO antenna obtained by breaking up an intact rectangular patch into a 2 x 5 small patch array with connected strips is proposed for 5G mobile terminals. The diagonal small patches are connected with the metal strips respectively, so as to constitute an interleaved double branch composed of a main branch and a parasitic branch, thus achieving compactness. The main branch fed by two ports operates at 4.5 GHz, and the parasitic branch coupled by the main branch achieves a lower resonant frequency of 3.35 GHz, thus widening the bandwidth. The small patches in the middle are connected to the ground to improve the isolation. A short length of 21.5 mm (about 0.24 wavelength of the lower-edge frequency) of the proposed antenna pair is realized. Besides, an eight-element MIMO antenna is designed and fabricated. Measured results show the reflection coefficients are lower than -6 dB, and the transmission coefficients between every two ports are lower than -10 dB in the 5G N77/N78/N79 bands (3.3-5.0 GHz). The average total efficiencies are 70.4% and 63.8% for antenna 1 and antenna 2, respectively. The ECCs are lower than 0.15.