Dual-band Isolation Enhancement of Antennas Using a T-Shaped Isolator

This study proposes a T-shaped isolator design to reduce mutual interference between dual-band planar inverted-F antennas (PIFAs) in multiple-input multiple-output (MIMO) systems for mobile devices. A T-shaped isolator was designed to independently control the resonance of each frequency band using two lumped capacitors. Through simulations, we verified that the resonance frequency of the isolator changed independently with variations in the capacitance values for each frequency band. We also analyzed the impact of the isolator size on isolation performance and observed improved isolation as the isolator size increased. With the isolator, the coupling coefficient between the antennas remained below −13 and −17 dB for the low and high bands, respectively.