Characteristic Mode Analysis of Neutralization Line for MIMO Antenna Designs

This paper presents a novel method using characteristic modes theory (TCM) to design the neutralization line (NL) for a dual-band multiple-input multiple-output (MIMO) antenna to achieve decoupling. A properly designed arc metal NL introduces new characteristic currents which in the opposite direction to the original characteristic currents thus achieving the effect of decoupling greater than 30 dB at resonance point. Simulated results show that the impedance bandwidths of the antenna are 0.42 GHz (2.27–2.69 GHz) and 0.83 GHz (5.01–5.84 GHz) when
$S_{11}\leq-10\ \text{dB}$
, and the relative bandwidths reach 16.1% and 19.3%, respectively, which is suitable in WLAN wireless communication system.