Contribution to the design of MIMO Ultra -Wide bande monopole antenna

Abstract

This work presents the design UWB MIMO antennas with reduced Mutual coupling. The work is started by the design and analysis of a rectangular monopole that operates as UWB structure. The Bandwidth is further enlarged by introducing the concavities in the non-radiating edges of the rectangular monopole. The obtained structure conserves the far field characteristics with an increase in the bandwidth. The design is extended to two rectangular monopoles for MIMO applications. The observed mutual coupling is reduced by embedding a rectangular metallic isolator between the patches. A further decrease in the mutual coupling is carried out by replacing the rectangular monopoles by concaved monopoles. Eventhough isolation between the elements of the MIMO structures is reached; the main beam radiation direction is deflected opposite to the isolator wall in the E-plane with high level cross-polar component in the H-plane. To confirm the near zone results, the concaved MIMO structure fabricated on the FR4 dielectric substrate. The measurements of the input reflection and the transmission coefficients present agreement with simulations within the limits of measurement conditions.