###### Abstract  
This study introduces a cost-effective monopole antenna array and its MIMO configuration. The single element consists of a rectangular patch monopole featuring five circular slots at the center, accompanied by two thin slots at the top, offering a wide bandwidth (2-7.62 GHz) and a peak gain of 3.8 dBi. For gain improvement, a 2 \(\times\) 1 antenna array is demonstrated. This antenna array exhibits dual-band behavior; spans from 2 to 3.71 GHz and from 5.9 to 7.54 GHz; covers the 2.5 GHz band (2.3-2.7 GHz), a significant portion of the n78 band (3.3-3.71 GHz), and the n96 band (5.925-7.125 GHz); and is assigned to WiMAX, sub-6 GHz, and sub-7 GHz applications, respectively. The antenna array achieves a peak gain of 6.47 dBi. Lastly, a two-element MIMO configuration derived from the 2 \(\times\) 1 array is designed. Implementing a defected ground structure (DGS) on the ground plane plays a crucial role in enhancing the isolation from 7 dB to 20 dB. The presented MIMO antenna covers the desired frequency bands of 2.5 GHz, n78, and n96 with a peak gain of 7.5 dBi and high radiation efficiency (<99%), which qualifies it for WiMAX, sub-6 GHz, and sub-7 GHz applications. array antenna; dual-band; WiMAX; sub-6 GHz; sub-7 GHz; MIMO; 5G 2024131502202413150224131  
LTE band 42 (3.4-3.6 GHz), LTE band 43 (3.6-3.8 GHz), LTE band 46 (5.1-5.8 GHz), n96 (5.925-7.125 GHz), and others. The research detailed in [9] presents a four-element MIMO antenna for 5G applications. To improve isolation between adjacent antennas, a shared grounding branch is employed as a decoupling structure. Operating within the frequency bands of 3.5 GHz and 4.9 GHz, this MIMO antenna provides minimum isolations of 17 dB and 20 dB, respectively. In [10], a four-port, two planar inverted-F antenna (PIFA) element is reported. To achieve spatial diversity, the two antennas are diagonally positioned on opposite sides. The implementation of the defected ground structure technique reduces mutual coupling between the ports by minimizing the current flow between them. This antenna spans a frequency range of approximately 2.7 to 3.6 GHz, with an isolation exceeding 13 dB. The work described in [11] introduces a four-element MIMO antenna designed for 5G cell phone applications. The unit element is composed of a monopole antenna, a planar inverted-F antenna, and a slot implemented using a defected ground structure (DGS). The antennas are positioned at right angles to each other at the corners of the substrate. The MIMO antenna operates between 3.3 and 5.8 GHz, delivering a satisfactory gain of 3.5 to 6 dBi while keeping the isolation level above 15 dB. In [12], a MIMO antenna module designed for fifth-generation smartphones is introduced. The module contains radiating metal strips and two feeding ports. Enhancements of the isolation between ports and between modules include the incorporation of a chip capacitive decoupler and spiral slots. With a minimum isolation of 12 dB, the two ports' measured \(-\)6 dB bandwidths are 310 MHz (3.42-3.73 GHz) and 360 MHz (3.33-3.69 GHz), respectively. In [13], a six-element MIMO antenna for 5G sub-6 GHz applications is presented. The single antenna utilizes a loop-type configuration. Two antennas are positioned in the center of the PCB, and four antennas are positioned at the corners for pattern diversity characteristics. The MIMO antenna operates in the 2.38-2.72 GHz and 3.17-3.84 GHz frequency bands, providing a peak gain of 6 dBi, with inter-port isolation exceeding 10 dBi. In [14], an eight-element MIMO antenna for sub-6 GHz and WLAN applications is presented. The MIMO antenna has a bandwidth of 2.7 GHz, specifically ranging from 3.3 to 6 GHz, and a compact size of 72 \(\times\) 72 mm\({}^{2}\). To enhance isolation across the desired frequency bands, triangle-shaped slots and a T-shaped stub were utilized. The MIMO antenna achieves more than 2.5 dBi peak gain, with more than 15 dB port-to-port isolation. In [15], a novel MIMO antenna with dual-band capability and four ports is discussed.