Isolation enhancement for four‐element MIMO antenna by using novel meandering technique

The paper proposes a four‐element printed multiple‐input‐multiple‐output (MIMO) antenna with high isolation achieved by employing a compact decoupling method. The optimal shaping (meandering) of the monopole strip is adopted to realize decoupling at the working frequency band ranging from 5.004 to 5.320 GHz. The ports isolation S 21 ${S}_{21}$ and S 41 ${S}_{41}$ are improved by using self‐meandering technology with transmission zero occurring at the frequencies of 5.004 and 5.320 GHz, respectively. Meanwhile, the isolation S 31 ${S}_{31}$ is also greatly increased. The decoupling technique can significantly improve the isolations between the four ports of the proposed antenna, without the extra‐added structure. A four‐element MIMO antenna with an edge‐to‐edge spacing of 0.069 λ 0 ${\lambda }_{0}$ ( λ 0 ${\lambda }_{0}$ is the wavelength at 5.162 GHz in free space) is fabricated and measured. In the experiment, the proposed MIMO antenna has a relative bandwidth (reflection coefficient of −10 dB) of 6.12% with a range from 5.004 to 5.32 GHz. In addition, this design can significantly obtain higher port isolation, antenna efficiency, gain, and a lower envelope correlation coefficient (ECC).