Compact Wideband High-Gain Quad-Port Octagonal MIMO Antenna with Fractal Elements for mm-Wave 6G Applications

A fractal element quad-port, compact, wideband, octagonal MIMO antenna with defected ground geometry (DGG) is presented for advanced mm-wave 6G and beyond applications. The presented MIMO antenna system, with dimensions of 40.28 × 40.28 × 1.58 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup>, incorporates a shared ground plane essential for real-time communication systems. Constructed with copper for the conductive patch and ground, and Rogers RT Duroid 5880 (ϵr=2.2, tanδ=0.0009 and thickness h=1.58 mm) as the substrate, the design achieves optimal compactness and is ideal for installations that require minimal impact. The unique geometry supports a broad operational bandwidth from 35.5 to 60 GHz (Impedance bandwidth of 2.5.4 GHz 51.31%), covering essential mm-wave frequency bands for 5G, 6G, and satellite communications, along with potential applications in vehicular radar and high-speed point-to-point communications. It exhibits exceptional isolation between elements, with values exceeding 20 dB, a peak gain of over 14.3 dBi, and efficiency above 95%, making it highly suitable for energy-efficient, high-performance mm-wave systems. MIMO performance parameters indicate robust diversity and isolation, with a diversity gain (DG) of over 9.99 dB, an envelope correlation coefficient (ECC) below 0.01, and stable directional radiation patterns. 5G MIMO, 6G, and other high-capacity data transmission applications that use mm-wave technology for improved spatial diversity, less interference, and dependable high-speed connectivity are confirmed by these properties and the strong inter-element isolation.