Dual polarized triple band 4×4 MIMO antenna with novel mutual coupling reduction approach

Abstract

A 4-port Multiple-Input-Multiple-Output (MIMO) antenna with tri-band frequency operation covering GSM (IEEE-802.21), WiMAX (IEEE-802.16) and WLAN (IEEE-802.11n) bands for modern wireless broadband communication applications has been designed and investigated. Proposed MIMO antenna has linearly polarized (LP) GSM band and circularly polarized (CP) WiMAX, WLAN bands poses ≤ 3dB axial ratios (AR), demonstrating dual polarized operations amongst existing three bands. Proposed 4×4 MIMO antenna attains reflection coefficient magnitudes S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> , S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">22</sub> , S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">33</sub> , S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">44</sub> ≤ -10dB at mentioned three bands. The proposed antenna is fabricated on a low cost FR4 substrate and has total geometry of 165×165 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Presented antenna accomplishes 96 MHz axial ratio bandwidth (ARBW) at WiMAX and 201 MHz at WLAN band. With novel mutual coupling reduction approach of integrated parasitic strips and inverted ground plane structure a highest isolation of S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> , S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">31</sub> , S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">41</sub> , ≤ -45dB has been achieved. Deployment of inversions in ground planes does not affect the intended polarization properties when numbers of antenna elements are increased for MIMO applications.