Four Element UWB MIMO Antenna with Improved Isolation Using Resistance Loaded Stub for S, C, and X Band Applications

Abstract

—This article proposes a four-port multiple input multiple output (MIMO) ultra-wideband (UWB) antenna that operates across 3 to 13 GHz. Four identical fractal patches are placed orthogonally to each other. The uniqueness of the proposed design is that it does not need to incorporate any dedicated/specific design/component to realize notches within the UWB range. The elimination of notches, enhancement of bandwidth, and improvement of isolation have been achieved by integrating a resistance-loaded stub with the ground plane. The isolation between the elements was measured to be below −20 dB across the entire operating band. The fabricated prototype exhibits better diversity parameters like envelop correlation coefficient (ECC) < 0.003, diversity gain (DG) > 9.99, channel capacity loss (CCL) < 0.4 bps/Hz, and mean effective gain (MEG) < 2 dB. The proposed MIMO antenna shows omnidirectional radiation patterns with a peak gain of 5.4 dBi and radiation efficiency > 66% with required compactness having interelement (edge to edge) distance of 5.4 mm. After application of decoupling method radiation efficiency varies from 66% to 82% with gain ranging between 1.8 and 5.54 dBi. The diverse performance of the fabricated MIMO proves it to be a good candidate for UBW imaging, LTE applications, and S, C, and X band applications.