Dual Band MIMO Antenna with High Isolation for GSM and WLAN Applications

Abstract

We propose a compact dual-band MIMO antenna for GSM 1800 MHz and WLAN applications. A novel single branch dual band antenna consisting of a quarter annular ring and an inverted U-shaped strip is designed by decreasing the electromagnetic coupling between higher order modes of an annular ring ultra-wideband (UWB) antenna, and a simple technique of slots and I and L-shaped stubs protruding from ground plane is employed to achieve high isolation. S11 < −10 dB over 1.704–1.934 GHz and 5.66–6.25 GHz frequency range and mutual coupling S12 < −20 dB and < −28 dB over the two bands are achieved. The radiation pattern, envelope correlation coefficient (ECC), total active reflection coefficient (TARC), diversity gain (DG), and mean effective gain (MEG) conform to MIMO specifications. The prototype antenna is fabricated on a 0.244λ0 × 0.17λ0 FR4 substrate, where λ0 is the free-space wavelength at 1.7 GHz. The antenna offers stable radiation patterns. The antenna is compact, simple to design, easy to fabricate, and low in cost. These characteristics depict the suitability of this antenna for portable wireless devices.