Novel Slot-MIMO Antenna Approach for Improved Connectivity in Sub-6 GHz Applications

This paper presents a proposed Slot-MIMO antenna with two identical ports, each port is fed through 50-Ohm microstrip line to operate within the sub-6 GHz (3.5-4.5 GHz) for fifth-generation (5G) cellular phone applications. The proposed MIMO antenna has been designed on FR-4 dielectric substrate (ɛ = 4.4, δ = 0.025, and h = 1.6 mm). The ground has two basic slots, one square slot radiator, and one irregular square slot radiator filled with a Diamond conductor shape. In addition, the ground has a DGS structure (8-slots) beside the two basic slots. The ground DGS is used to adjust the resonance frequency as well as to reduce the mutual coupling between the ports. The simulated result indicated that the proposed MIMO antenna has a gain of about 2.5 dBi and an impedance bandwidth of 614 MHz at the -10-dB (3.751-4.365 GHz). However, an impedance bandwidth of 1180 MHz at -6-dB (3.32-4.5 GHz) is achieved. The mutual coupling is less than -24 dB overall the bandwidth, and the efficiency is more than 80% at the antenna resonance frequency (4.15 GHz). This antenna has been implemented and measured, and the results have been agreed with the simulated ones. In addition, the proposed Slot-MIMO antenna can be used as a MIMO antenna-cell with the smartphone. Many MIMO cells can be etched on the smartphone motherboard to improve connectivity with high isolation.