Isolation Enhancement in MIMO Arrays for UWB Applications

An effective technique is proposed which decreases the mutual coupling (MC) between four orthogonally placed strip line-fed micro strip elements operating for the UWB frequency range in MIMO configurations. The fraction of MC decreased is achieved via placing U-shaped stubs at the center of each of the circular patch elements which in turn helps to modify the antenna polarization. The spacing between four elements is 15.5mm. In this paper we design the four elements orthogonal in terms of polarization via placing U-shaped slots at the center of each radiator. The U-shaped slots used in circular patch achieves isolation greater than or equal to 15 dB with return loss less than −10db for the entire UWB range. In order to validate the technique, a four-element MIMO antenna placed orthogonally is designed, and simulated. The reliability of the suggested technique is evaluated using generated results in terms of MC, peak gain and radiation pattern. The isolation between the four elements has been enhanced from 2.8 dB to 20 dB for the UWB frequency band, as demonstrated by simulation results.