A compact quad-band four-port MIMO antenna decoupled by power divider for intelligent driving

A compact quad-band, four-port multiple input multiple output (MIMO) antenna for intelligent driving environments is developed and experimentally verified. The antenna employs a dual-layer structure to reach a compact design. Each unit consists of two multi-branch antennas, which are mirror-symmetrically placed. Such unit antennas are useful to enhance gain. Each unit antenna is fed using a SMA port, followed by a power divider. The power divider is intentionally designed, functioning as power division, impedance matching and reducing coupling. By taking advantage of these techniques, it is demonstrated that four frequency bands (3.24-3.45 GHz, 4.58-4.95 GHz, 5.73-6.48 GHz, and 7.36-8.39 GHz) are realized, covering applications such as V2X (5.905-5.925 GHz), and Wi-Fi 6E (5.925-6.425 GHz). It is found that the coupling coefficient is below -32 dB in the V2X frequency band, and the envelope correlation coefficient is below 0.03. A high diversity gain exceeding 9.85 dB is realized, with the channel capacity loss < 0.4 bit s-1 Hz-1, and the total active reflection coefficient nearly below -10 dB. These facts suggest that the proposed antenna is a well-qualified candidate for multi-band automotive communications.