A Wideband Printed Dual-Antenna With Three Neutralization Lines for Mobile Terminals

Abstract

A wideband printed dual-antenna for mobile terminals is studied. The dual-antenna, consisting of two symmetric antenna elements and three neutralization lines (NLs), is printed on a printed circuit board. The three NLs reduce the mutual coupling within a wide frequency band. The working mechanism of the three NLs is analyzed based on the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$S$</tex></formula> -parameters, the surface current distributions, and a simplified equivalent model which provides intuitive instructions to optimize the three NLs. A prototype shows that the measured <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 impedance bandwidth is 1.3 GHz (1.62–2.92 GHz) and the measured mutual coupling is 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> 15 dB at the 1.66–2.84 GHz band. It covers the GSM1800, GSM1900, UMTS, LTE2300, LTE2500, and 2.4-GHz WLAN bands. The radiation patterns are measured and the diversity performances are evaluated.