Characterization and Performance of an Ultra-Wideband Wide Coverage Multimode MIMO Antenna

A new ultra-wideband multimode (MM) antenna design that enables the detection/transmission of two orthogonal field components over a nearly hemispherical coverage area is presented in this paper. It integrates and colocates two perpendicularly oriented bow-tie dipole elements, a short convex monopole and four horizontally oriented tapered slot antenna (TSA) elements (formed by the dipoles) in order to produce four decoupled and complementary gain patterns. The antenna feeding structure includes four single-ended transmission lines supporting the desired set of individual excitation modes. Experimental verification confirms the predicted negligible coupling between the antenna operating modes and orthogonality of the corresponding radiated field patterns. These unique features can be exploited in applications where pattern and polarization diversity are of importance. In this study, we have evaluated the proposed antenna as a MIMO base station antenna and characterized it in two different propagation scenarios. For this example, it has been shown that the utilization of the additional monopole and TSA modes plays an important role in maximizing MIMO efficiency in line-of-sight (LOS) scenarios and at the same time provides additional independent data streams in rich scattering scenarios. In both considered scenarios, the antenna is shown to have a MIMO frequency bandwidth of 85%.