###### Abstract  
In this paper, the design, simulation, fabrication, and characterization study of a low-cost and directional hybrid four-element (2 \(\times\) 2 configuration) Minkowski-Sierpinski fractal antenna array (MSFAA) for the high-efficiency IEEE 802.11 ax WLANs (Wi-Fi 6E) and the sub-6 GHz 5G wireless system is presented. Each element of the array is separated by 0.7 \(\lambda_{0}\). The complete four-element fractal antenna array system includes designing the single-element Minkowski-Sierpinski fractal antenna using two different substrates for performance comparison and an equal-split Wilkinson power divider (WPD) to achieve power division and to form a feed network. The single-element antenna, four-element fractal antenna array, and WPDs are fabricated using a flame-resistant (FR4) glass epoxy substrate with a dielectric constant (\(\epsilon_{r}\)) of 4.3 and thickness (\(\mu\)) of 1.66 mm. For performance comparison, a high-end Rogers thermoscal microwave material (TMM4) substrate is also used, having \(\epsilon_{r}\) = 4.5 and \(h\) = 1.524 mm, respectively. The designed four-element fractal antenna array operates at the dual-band frequencies of 4.17 and 5.97 GHz, respectively. The various performance parameters of the antenna array, such as return loss, bandwidth, gain, and 2D and 3D radiation patterns, are analyzed using CST Microwave Studio. The fabricated four-element antenna array provides the bandwidth and gain characteristic of 85 MHz/4.19 dB and 182 MHz/9.61 dB at 4.17 and 5.97 GHz frequency bands, respectively. The proposed antenna array design gives an improvement in the bandwidth, gain, and radiation pattern in the boresight at both frequencies. In the IEEE 802.11 ax WLANs (Wi-Fi 6E) deployments and the upcoming 5G wireless and satellite communication systems, it is critical to have directional antenna arrays to focus the radiated power in any specific direction. Therefore, it is believed that the proposed dual-band four-element fractal antenna array with directional radiation patterns can be an ideal candidate for the high-efficiency IEEE 802.11 ax WLANs (Wi-Fi 6E) and the upcoming 5G wireless and satellite communication systems. 202  
increasing, and currently, \(\sim\)23 billion wireless devices are connected to the internet. It is predicted that these devices will increase to 75 billion by 2025 [4]. Initially, in order to meet the ever-increasing high throughput per user demand both for home users and in high-density places such as offices, stadiums, train stations, and airports, etc., the IEEE introduced an enhanced version of IEEE 802.11 ac [5] standard, which is commonly referred to as IEEE 802.11 ax or Wi-Fi6 [6]. The 802.11 ax has the ability to deliver 9.6 GB/s data rates, which is 37% higher than its predecessor, 802.11 ac [6]. Another important feature of this technology is that it exploits both the 2.4 and 5 GHz frequency bands simultaneously. In the future, 802.11 ax technology will also be available in the 6 GHz band as part of Wi-Fi 6E [6]. Then, technological growth of the fifth-generation (5G) wireless systems [2,3] will be needed to meet this high demand for the network. The emerging 5G system will provide the end-users with benefits such as improved data rates, less power dissipation, and reduced over-the-air latency, with an improved overall system capacity of several billion users [1, 2, 3]. Another important feature of the 5G technology is the exploitation of both microwave (around 3-6 GHz) and millimeter-wave (mmW) frequency bands [1, 2, 3, 7]. This provides enhanced spectral utilization and leads to the requirement of antenna arrays with beam-steering capabilities to focus radiated power in any specific direction. The 5G technology is expected to provide enhanced quality of service (QoS) with constant connectivity to end-users who demand anytime, anywhere, and with-anything connectivity [2, 3, 4, 5, 6, 7].