###### Abstract  
A low-profile Multiple Input Multiple Output (MIMO) antenna showing dual polarization, low mutual coupling, and acceptable diversity gain is presented by this paper. The antenna introduces the requirements of fifth generation (5G) and the satellite communications. A horizontally (4.8-31 GHz) and vertically polarized (7.6-37 GHz) modified antipodal Vivaldi antennas are simulated, fabricated, and integrated, and then their characteristics are examined. An ultra-wideband (UWB) at working bandwidths of 3.7-3.85 GHz and 5-40 GHz are achieved. Low mutual coupling of less than \(-22\) dB is achieved after loading the antenna with cross-curves, staircase meander line, and integration of the metamaterial elements. The antennas are designed on a denim textile substrate with \(\epsilon_{r}=1.4\) and h = 0.5 mm. A conductive textile called ShieldIt is utilized as conductor with conductivity of \(1.8\times 10^{4}\). After optimizing the proposed UWB-MIMO antenna's characteristics, it is increased to four elements positioned at the four corners of a denim textile substrate to be employed as a UWB-MIMO antenna for handset communications, 5G, Ka and Ku band, and satellite communications (X-band). The proposed eight port UWB-MIMO antenna has a maximum gain of 10.7 dBi, 98% radiation efficiency, less than 0.01 ECC, and acceptable diversity gain. Afterwards, the eight-ports antenna performance is examined on a simulated real voxel hand and chest. Then, it is evaluated and compared on physical hand and chest of body. Evidently, the simulated and measured results show good agreement between them. The proposed UWB-MIMO antenna offers a compact and flexible design, which is suitably wearable for 5G and satellite communications applications. MIMO antenna; 5G communication; satellite communication; UWB antenna; isolation;ivaldi antenna; metamaterials +
Footnote †: journal:  
0000-0001-9599-22001/12/15/00000-00001-9599-22001/12/15/0000000-00001-9599-2201/12/15/00000000-000000-000000-000000-000000-0000000-0000000-00000000-00000000000000000000000000  
performance if they face an environment except air [4]. Moreover, wearable designs should adhere to regulations for absorption rates (SARs). Numerous two-dimensional structures such as metamaterial (MTM) structures [5; 6], ferrite sheets [7; 8], soft surfaces, frequency selective surfaces (FSS), and large ground planes [9; 10] have been employed as insulating layers in body area network (BAN) applications to shield the human body from the harmful radiation [11; 12; 13]. In cellular communication, as the number of users grows, the frequency provision becomes insufficient due to limited channel capacity. Within the same frequency band, the number of operators cannot go beyond a certain limit. As the total users grow so does co-channel interference. The capability of transiting data using 3G and 4G frequency channels is restricted, streaming videos and transferring big files problematic. Larger bandwidths and quicker communication channels are required [14]. The primary spectrum bands between 2 GHz and 6 GHz are between 3.3 GHz and 4.2 GHz, and between 4.4 GHz and 4.990 GHz. These bands are now being evaluated for 5G network early testing in several countries [15]. Furthermore, several higher bands, such as 24-27.2 GHz, 33-44.13 GHz [16], 26-31 GHz [17], and 28-38 GHz [18], are also considered 5G. 5G and MIMO communication systems are two of the most significant developments in boosting bandwidth (MIMO). On the other hand, ultra-wideband (UWB) systems have numerous benefits, including a very wide bandwidth, low power consumption, a high data rate, a high temporal resolution, resistance to interference, coexistence with narrowband systems, and so on. As a result, UWB technology is widely utilized in communication, radar, imaging, and localization [19]. Multi-input-multiple-output (MIMO) technology can be used with UWB technology to increase transmission rate and communication dependability.