Mutual reduction in the coupling of the MIMO antenna network applied to the broadband transmission

Abstract

In this article, a new form of UWB (ultra-wide-band) antenna operating to the desired specifications, obtained from a base antenna to which some modifications are made. The proximity of the antennas causes a mutual coupling phenomenon thus generating an apparent modification of their characteristics. It is therefore crucial to have the minimum level of insulation with a small possible separation distance between the antennas to ensure efficient operation of our multiple input and multiple output (MIMO) system. The separation spacing between the antennas is close to 0.15λ0 (λ0 is the wavelength in free space), where the coupling can be very weak. To overcome this weakness, two efficient methods are applied to minimize mutual coupling in a four-element MIMO antenna, such as the use of the neutralization line and the use of split ring resonator metamaterial (SRR). The objective of our paper is, on the one hand the design of UWB antenna, and on the other hand to minimize the coupling between four UWB-MIMO antennas using the two methods of isolation mentioned above. A coupling minimization of more than 15 dB is obtained using the neutralization line and more than 20 dB with the use of metamaterial while maintaining the operating band and radiation specifications of the MIMO antennas.