Four-element equilateral triangular-shaped MIMO antenna with connected ground for 5G sub:6 GHz N79 and WiFi-6E band applications

The present communication presents a novel compact microstrip line feed dual-band four-element MIMO (multiple input multiple output) antenna for 5G sub-6GHz N79 and WiFi-6E bands with a defined size of 48 x 48 x 1.6 mm(3). The FR4 substrate used in the construction of the designated antenna has a thickness of 1.6 mm, a relative permittivity of 4.4, and loss tangent values of 0.02. The proposed MIMO architecture consists of four equilateral triangle-shaped antenna elements on top and ground with inverted L-shaped stubs on the substrate's bottom layer. The ground structure of the antenna is a connected ground and is formed by defected ground parts which are connected with inverted L-shaped stubs. The orthogonal structure of the MIMO antenna elements, with four armed square stubs among them, enhanced the isolation between surrounding antennas. The proposed four-port MIMO antenna is built and tested in to validate design, scattering, and radiation performance, as well as MIMO diversity features. The designed antenna has more than 15 dB isolation and operates at 4.75 GHz from 4.45 to 5.2 GHz (5G sub-6 GHz N79 band) and 6.3 GHz from 5.95 to 7.15 GHz (WiFi-6E band). Furthermore, the design provides omnidirectional patterns, high gain (6.5dBi) and efficiency (>95%), a low envelope correlation coefficient (<0.00001) and acceptable diversity gain (10 dB), a good total active refraction coefficient (-10 dB) and low channel capacity loss (0.03 bit/s/Hz), and a considerable mean effective gain (MEG = -3 dB) and MEG ratio (0 dB). Because the simulated and tested results match so well, the antenna is a good candidate for 5G sub-6 GHz N79 band operations.