A Compact Ultrawideband MIMO Antenna With WLAN Band-Rejected Operation for Mobile Devices

Abstract

This letter presents an ultrawideband multiple-input–multiple-output (MIMO) antenna that covers the WCDMA (1.92–2.17 GHz), WiMAX (2.3, 2.5 GHz), WLAN (2.4 GHz), and UWB (3.1–10.6 GHz) bands for wireless device applications. The proposed antenna consists of a printed folded monopole antenna coupled with a parasitic inverted-L element, with an open stub inserted in the antenna to reject the WLAN (5.15–5.85 GHz) band that interferes with the UWB band. These two antennas are symmetrically arranged on a mobile device substrate. The <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$-$</tex></formula> 10-dB bandwidth of the designed antenna is 1.85–11.9 GHz without the WLAN band 5.15–5.85 GHz. <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${ S}_{21}$</tex></formula> and the envelope correlation coefficient are lower than <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$-$</tex></formula> 17.2 dB and 0.18 in the operating bands, respectively. The size of the antenna is <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$55\times13.5 ~{\hbox{mm}}^{2}$</tex></formula> .