An SRR-Loaded Compact Triple-band 4-Element MIMO design for WLAN/WiMAX/C-band Applications

Abstract

A planar compact triple-band quad-element MIMO design with polarization diversity is proposed in this work for WLAN (2.4 GHz), WiMAX (3.5 GHz), and C-band applications. The MIMO antenna element with a compact size (15 × 24 mm2 ) comprises of Split-Ring Resonator (SRR) loaded open square-loop monopole (OSLM). Four such antenna elements are placed at the corners of an FR-4 square substrate of dimensions 55 × 55 mm2 with an orthogonal orientation of adjacent elements to implement quad-element MIMO geometry. Elements' position offsetting and trimming the substrate area of Loff × Woff at each corner leads to a reduction of cost and footprint. The proposed MIMO design is resonating at 2.44, 3.5, and 4.3 GHz and accomplishes an -10 dB return loss bandwidths of 85 MHz (2.4 – 2.485 GHz), 370 MHz (3.33 – 3.7 GHz), and 660 MHz (4.0 – 4.66 GHz) in the lower, middle and higher working bands. Despite its compact size, it reports good minimum isolation of 15.2 dB across all three bands. It provides stable omnidirectional radiation characteristics in all the operating bands. The diversity performance is verified with its envelope correlation coefficient (ECC) and Diversity Gain (DG) metrics. The proposed MIMO geometry can be a good candidate for portable wireless devices due to its compact feature with good radiation/diversity performance