Design of high port isolation access point MIMO system using centrally located hexahedron

Abstract

A novel dual-band multiple-input multiple-output (MIMO) antenna system with diversity polarisation and high port isolation is proposed. The antenna system consists of six antennas (three antennas operate at 2.44 GHz and the others at 5.25 GHz) mounted on a hexagon ground plane and backed by a centrally located hexahedron. The antennas for different bands are arranged in an alternative fashion along the peripheral of the hexagonal ground. From simulation and experimental results, the proposed MIMO system has been shown to perform superbly at both the 2.44 and 5.25 GHz bands, with significant and consistent improvements in sidelobe levels and envelope correlation coefficients at the lower band due to the presence of the hexahedron.Introduction: Multiple-input multiple-output (MIMO) technology has been widely adopted to increase data throughput without employing an extra spectrum. In fact, many 802.11n [1] wireless products, which utilise the MIMO antenna system, are readily available in the marketplace. Numerous research papers on MIMO antennas embedded in mobile devices, i.e. the client end, have been reported [2,3]. The designs usually focus on decoupling techniques because of a limited system circuit-board space designated for the antennas. Meanwhile, only a few studies have been published [4,5] for access-point (AP) applications, i. e. the server end. In this Letter, we present a concurrent MIMO antenna design, consisting of six antennas for AP applications. Three of them operate at 2.44 GHz, and the other three at 5.25 GHz. They were alternatively co-located along the peripheral of a hexagon ground plane, backed by a hexahedral metal structure for in-band isolation improvement. The Letter shows the performance improvement due to the hexahedron.