The proposed design is employed on a Rogers 4350B laminate with a thickness of 0.8 mm. The antenna has a simple structure which is excited using a 50-Ω feedline. These slots extend the physical separation between the resonators, resulting in high isolation 22. The antenna elements are rotated at 45° in the clockwise direction, and two slots are introduced in the radiating part to achieve better isolation in these closely packed elements. This study proposes a low-cost, low-profile, miniaturized two-element-based MIMO antenna system with significantly reduced mutual coupling of S21 < − 36 dB. Each neutralization line consists of metal strip and in the middle of antenna elements a reactive component attached. In 21, neutralization line is presented for the first time to achieve isolation enhancement. In 20, a Y-shaped stub ensued by rectangular slots in the ground plane was employed for better isolation between wrench MIMO antennas. An electric-LC resonator was used at two-element MIMO antenna for mutual coupling reduction 19. In 18, parasitic F-shaped stubs were used between the radiating patches to achieve good isolation. Researchers have suggested remarkable techniques to reduced mutual coupling between the radiators, such as employing a defective ground plane 15, electromagnetic bandgap structures 16, and a perpendicular feeding network 17. Similarly a Wilkinson power divider is used as to enhance isolation between the radiators as shown in 14. In 13, a novel parasitic decoupling technique is proposed having efficiency more than 64% for closely coupled antenna. Similarly, mender line slots, L- and T-shaped ground branches were added to the ground plane resulting in high isolation at the cost of fabrication complexity 10, 11, 12. Another approach is to use slits in the ground plane, but it cause in backward radiation 9. In 8, six metal strips were incorporated between the radiators to efficiently reduce the mutual coupling without affecting the gain and radiation pattern. However, this approach increased the thickness of the antenna, reducing its wider applications in low-profile arrays. In 7, isolation was increase by adjusting the structure of the ground plane under each resonator in order to make mutual coupling out-of-phase between the ground plane and free space which cause in isolation enhancement by more than 10 dB between the diagonal and adjacent elements. A tree-shaped MIMO antenna structure was proposed in 6 with isolation > 16 dB over the entire ultrawide band. In 5, more than 20 dB isolation is observed among the MIMO patch antennas by using near field resonator above each antenna elements. In 4, a stub on the lower ground plane was used in perpendicularly placed radiators to achieve minimum mutual coupling. Different approaches have been recommended by the researcher to reduced mutual coupling between the radiators. Thus, optimizing mutual coupling would be significant in wireless communication systems.Ī MIMO antenna incorporates minimum two radiating elements, placed at a specific distance to achieve minimum mutual coupling between them, but very limited space is available in front-end modern communication systems. Researchers have attempted to develop methods to maximize the packing density while enhancing the isolation between the radiators. Increasing the physical distance between the radiators is a simple manner to achieve high isolation, but it results in a large antenna size. However, mutual coupling due to surface wave propagation and inadequate isolation among the elements of a massive MIMO system causes poor impedance and radiation performance and degrades channel capacity 3. MIMO technology is highly recommended owing to its promising features of enhanced data transmission speed, coverage area, and resistance to multiple paths fading 1, 2. With the increasing demand for high data rates, MIMO antennas have gained significant attention and are considered a key technology in millimeter-wave communication.
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