## 3 The UWB-MIMO MTM-Based MAVA for Diversity Analysis  
The proposed MAVA were positioned at the edges of a flexible denim comparable for 5G communication applications having a total size of 50 \(\times\) 45 mm\({}^{2}\) (width \(\times\) length), as shown in Figure 18a,b, to produce a MIMO configuration using the suggested antenna. Figure 19a,c,d shows the constructed flexible MIMO antenna and its measurement setup in the free space. The S-parameter of the flexible eight-ports is measured by connecting port 1 to PNA terminal 1 and the remaining ports to PNA terminal 2 (P\({}_{1}\) sends and P\({}_{2}\)-P\({}_{8}\) receive). Figure 20a shows the simulated S\({}_{\text{nn}}\) (n is the number of ports) for an eight-port MIMO antenna. In Figure 20b, the S\({}_{21}\)-S\({}_{28}\) for the antennas are presented. Even in the worst situation, which occurred between ports 1 and 2, the transmission coefficient data reveal a level of less than \(-\)22 dB. Within the whole frequency band, the suggested MTM-based antenna has a radiation efficiency of about 89 percent. It's worth noting that MTM array elements are utilized to improve the suggested antenna's maximum gain and efficiency, which are 10.7 dBi and 98 percent, correspondingly. The outcomes from the other ports are about equivalent to an individual antenna having modes of antennas. It will be informative knowing that since the ShiledIt is very sensitive towards hot soldering, we used conductive glue carefully. Because if the conductive glue used a lot around the port, the resistivity will be increased which degrades the antenna performance. Table 4 shows the gain calculated when port 1 and 2 are active, port 1 sends and port 2 receives. However, Figure 20 shows the reflection and transmission coefficients when port 1 sends and receives. The reflection and transmission coefficients are slightly different in working BW and poles, and their levels are also different due to the mutual coupling effects between each two ports. The difference in gain and efficiency is related to the loading that was used. For instance, the meander line was loaded to enhance the BW at lower band and improve the matching there. Therefore, the radiation characteristics of the antenna is higher there. Figure 17: Radiation patterns of MTM-based MAVA for port 2 at: (**a**) 3.8 GHz, (**b**) 5.4 GHz, (**c**) 8 GHz, (**d**) 12 GHz, (**e**) 18 GHz, (**f**) 22 GHz, (**g**) 25 GHz, and (**h**) 28 GHz in free space (black line: simulated co-polarization, red dashed line: measured co-polarization, on the \(xz\) plane). Figure 19: The MIMO antenna on a denim flexible board: (**a**) fabricated, (**b**) measurement setup on chest while laying down, and (**c**) measurement setup on chest standing in free space. Figure 20: Simulated frequency response results of the proposed MIMO antenna for a mobile handset communications co: (**a**) reflection and (**b**) transmission. The transmission coefficient experimental findings are shown in Figure 21. It shows that the MIMO antenna is effective over the full BW. Besides, there is strong isolation between the ports as indicated by the transmission coefficients of ports 1-8. The simulated and the measured results of the transmission coefficient yield the same pattern. One of the most important elements in evaluating the effectiveness of a MIMO antenna system is the Envelope Correlation Coefficient (ECC). It's used to figure out how comparable the antenna elements in a MIMO system behave and how much diversity there is between them. When ECC is less than 0.5 [71; 72], it might be considered acceptable. When