Design and verification of an umbrella shaped narrow band - UWB antenna pair for MIMO applications using characteristic mode analysis

Abstract

Using characteristic mode analysis (CMA), a pair of ultra-wideband (UWB) and narrow band antennas is made. The Multiple Input Multiple Output (MIMO) configuration incorporates a circular monopole to attain UWB functionality, while an umbrella-shaped element generates the narrowband operation. The two radiators are symmetrically positioned to accomplish space diversity. Distinct sizes of small electromagnetic band gap cells separate the two radiators. The MIMO structure has dimensions of 40×40×1.6 mm3 (0.32λo×0.32λo×0.12 λo) and improved isolation is accomplished by adding a T-shaped stub to the ground plane. The exceptional bandwidth of 11.6 GHz offered by the Circular-pot UWB antenna covers a frequency range from 2.4 GHz to 14 GHz. The antenna demonstrates favorable MIMO performance, featuring a gain of 4.9dBi, isolation exceeding 23 dB. The diversity characteristics encompass an enveloped correlation coefficient (ECC) of under 0.0012, a diversity gain (DG) approaching 10 dB, a channel capacity loss of 0.28 b/s/Hz, and a mean effective gain (MEG) measuring -3.3 dB. A favorable agreement between the tested and simulated results.