## 1 Introduction  
Mutual coupling effect is a serious problem in Multiple Input-Multiple Output (MIMO) antennas, and this problem occurs if the antenna elements are located very closely to each other. For example, if two planar antennas are located in a close range, one of these antennas radiates relatively as a function of the other antennas and vice versa [1]. In addition, it is expected for the antenna performances to be affected due to the close placement of the antennas. The physical spaces that host antennas (radio enclosures, antenna towers, etc.) are mostly limited, meaning it is inevitable to place multiple antennas and/or antenna elements very close to each other. This condition causes mutual coupling problems, that is, isolation problems. In recent years, various structures were designed and integrated with various antennas to overcome this problem and improve the efficiency of the antenna systems [2; 3; 4; 5; 6]. For instance, a wide band neutralization line [2] and meander line resonator [3] were presented in the literature to enhance mutual coupling between each antenna element of MIMO antennas. Moreover, metamaterials [4; 5] and metasurfaces [6], which are other artificial structures, were also used to minimize the mutual coupling effect in MIMO antenna applications. In addition, Electromagnetic Band Gap (EBG) structures are also used in mutual coupling reduction applications [7; 8]. [PERSON] et al. proposed a two layered EBG structure to reduce mutual coupling effects between ultra-wide band monopole antennas in a wireless communication band [7]. In addition, one dimensional EBG and split ring resonator structures were used to decrease the coupling problem of 2.45 GHz planar monopole antennas [8]. Similarly, [PERSON] et al. proposed a MIMO patch antenna configuration for a 5.8 GHz band in a ground plane to overcome this coupling problem between antenna elements [9]. In another study, [PERSON] and [PERSON] succeeded to reduce mutual coupling between nearest strip dipole antennas with the help of elliptical metasurface layers [10]. Moreover, [PERSON] et al. designed an array patch antenna configuration with the integration of an polarization conversion isolator to improve the antenna system parameters distorted by the coupling effect [11]. Additionally, there are many approaches and studies in the related literature focusing on improving the isolation by reducing the coupling effects between closely placed antenna elements in MIMO antennas [12; 13; 14; 15]. In one of the recent studies, a metamaterial absorber structure is designed and integrated to a four-element array antenna for 1.27 GHz band by [PERSON] et al. [14]. With these developed techniques, artificial neural networks provide accurate solutions and are used in many areas [16; 17; 18; 19; 20]. [PERSON] et al. used artificial neural network for analyzing and estimating microstrip circular patch antenna parameters in S frequency band regime [16]. In addition, [PERSON] et al. developed a method to compute the resonance frequency of metamaterial based patch antennas with the help of a artificial neural network [17]. In the same way, [PERSON] and [PERSON] used a artificial neural network approach to design a microstrip patch antenna with possible optimization values [18]. In another study, a novel artificial neural network model was developed to estimate antenna performance parameters in X band antenna applications [19]. As shown in a literature review, various structures were designed and developed for reducing the mutual coupling of cross antennas, while neural network approaches were used to enhance and estimate antenna performance parameters. In this study, a mutual coupling effect between each antenna element of cross dipole antenna is reduced and the isolation between them is improved by using an artificial neural network model. Firstly, an artificial neural network approach and working principle was given and the design phase of cross dipole antenna was presented for the 2.45 GHz frequency band.