A Compact Multi-Band MIMO Antenna With High Isolation and Low SAR for LTE and Sub-6 GHz Applications

This study designs a multi-band antenna that covers LTE, WiFi, Sub-6 GHz, and WiFi 6E frequencies, applying it to multi-input multi-output (MIMO) antenna systems in laptops, base stations, and smartphones. The antenna employs a microstrip structure and can achieve multiple frequency bands without passive component support. Different multi-band MIMO antenna systems can be configured using the same multi-band antenna structure, thereby reducing design complexity and manufacturing costs. The multi-band MIMO antenna system covers multiple bands and achieves an isolation level of −11 dB, a peak gain of 1.76 dBi, and an envelope correlation coefficient below 0.5. In this study, the antenna prototype is fabricated and measured to verify the performance of the three proposed multi-band MIMO antenna systems, with results showing strong consistency with the simulations. SAR analysis was also conducted for the proposed multi-band MIMO antenna system. The simulation results show that the SAR values are well below the standard limits. The proposed multi-band antenna has a straightforward and robust structural design. Its performance is minimally affected by the size of the device and the amount of antennas, demonstrating excellent safety characteristics. In the future, this antenna design will be able to connect seamlessly with electronic devices of various sizes, offering greater flexibility and scalability.