Design of a Hilbert Curve Fractal MIMO Slot Antenna With Enhanced Bandwidth and Stable Radiation Patterns for Wi-Fi 7 and Wi-Fi 8 Applications Using Genetic Algorithm

Next-generation Wi-Fi 7 (IEEE 802.11be) and Wi-Fi 8 (IEEE 802.11bn) demand compact multielement antennas offering wide bandwidth, high isolation, and stable radiation within limited device space. Conventional MIMO designs often face strong coupling, narrow bandwidth, or low efficiency, restricting high-throughput multilink performance. This work presents a Hilbert curve fractal (HCF) four-port MIMO slot antenna that leverages fractal self-similarity to extend the surface current path and excite multiple resonant modes within a compact size. The HCF slot supports TE₂₀ and TE₄₀ modes—TE₂₀ excites the lower 5-GHz band (5150–5945 MHz), while TE₄₀ generates a higher-order resonance in the 6-GHz band (6150–7150 MHz). Merging both bands allows for broadband dual-band operation. A defective ground structure reduces surface waves and improves isolation, while a genetic algorithm optimizes geometric parameters for wideband impedance matching across all four ports. The improved design has a measured bandwidth of 2125 MHz (5.0–7.125 GHz), a peak gain up to 6.51 dBi, radiation efficiency greater than 82%, and isolation up to −32 dB. The low ECC (< 0.005) and 10-dB diversity gain make it suitable for durable, high-capacity Wi-Fi 7, Wi-Fi 8, and future sub-6-GHz communication systems.