4-Port MIMO Antenna Using Common Radiator on a Flexible Substrate for Sub-1GHz, Sub-6GHz 5G NR, and Wi-Fi 6 Applications

Abstract

In this paper, an angular symmetric, common radiator coplanar waveguide (CPW) fed four-port multiple-input-multiple-output (MIMO) antenna is designed on a 0.129λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> L</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> RT Duroid ( ε <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> r</sub> = 3.0, tan δ = 0.001) substrate where λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> L</sub> is the free space wavelength at the lowest operating frequency ( f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> L</sub> ) of 0.6 GHz. The antenna has a -6 dB impedance bandwidth from 0.6-1.09 GHz, 2.6-3.4 GHz and 4.2-7.0 GHz to cover the emerging wireless communication bands. At the same time, it also has a -10 dB impedance bandwidth extending from 0.7-1.01 GHz, 2.6-3.18 GHz, 5.3-6.06 GHz, and 6.7-6.94 GHz. Design steps to enhance the operating bandwidth and the isolation in the sub-1GHz bands are presented. The antenna has a reasonable realized gain at the simulated and measured frequencies. It exhibits the pattern diversity which is useful for the MIMO implementation. The envelope correlation coefficient (ECC), Mean effective gain (MEG), and the channel capacity of the antenna have been computed from the measured results. In spite of the small circuit size at f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> L</sub> , the ECC ≤ 0.50 over the entire band is observed. In addition to the existing communication applications, this antenna can find newer applications in the emerging 0.6-1.09 GHz band, sub-6GHz 5G near radio (NR), and Wi-Fi 6 communications.