## 2 Configuration and Design of the Proposed UWB-MIMO Antenna
### Mava
Furthermore, \(r_{2}^{\prime}\) and \(r_{2}\) are the internal and external radiuses of the curved strip shown in Figure 1.  
To solve these equations, for instance for the curved stub, the input impedance for a stub loaded microstrip patch is calculated by the general planar dielectric dyadic Green's function approach in the spectral domain, as was initiated much earlier and has been extensively expanded upon and utilized successfully throughout the literature for microstrip antenna configurations. Using the spectral domain dyadic Green's function derived earlier [58] with the electric field integral equation, the problem is formulated by using entire domain basis functions to represent the surface current densities on the patch, the loading stub and the attachment mode at the junction. [PERSON]'s procedure can be used to reduce the electric field integral equation to a matrix equation, which is then solved to obtain the amplitudes of the surface currents. These surface currents are then used for calculating the input impedance of stub loaded rectangular and circular microstrip patches. Numerical results are compared with measured results and with previous results calculated by the [PERSON]'s theorem approach. More details about the equations and explanation are presented in [59]. The radiation region is formed by two MAVA patches. The patch and feed line dimensions of the first antenna are L\({}_{\text{p1}}\), L\({}_{\text{H}}\), W\({}_{\text{f1}}\), W\({}_{\text{p1}}\), W\({}_{\text{g1}}\), and L\({}_{\text{g1}}\), as illustrated in Figure 1. Equations (4) and (5) were used to calculate the actual size of the exponential ground section (the points location is shown by \(x\)). \[Y_{1}(x)=-\left(0.25e^{\frac{x-2}{2}}+6.5\right) \tag{4}\]  
\[Y_{2}(x)=-\left(0.24^{\frac{x-1}{2}}+5.8\right) \tag{5}\]  
This shape is utilized to reduce mutual coupling, heterogeneous tapering, create capacitive spaces for reduction of cross-polarization, and produce an input impedance of 50 ohm. Then, at the intersection of the feed line and patch, two cross curves with lengths of L\({}_{1}\), W\({}_{2}\), and radius of \(r_{4}\) were added to produce a pass band at 5.2 GHz. L\({}_{\text{p}}\), L\({}_{\text{f}}\), W\({}_{\text{f}}\), W\({}_{\text{p}}\), W\({}_{\text{g}}\), and L\({}_{\text{g}}\) are the second antenna's effective parameters. Their optimal values were displayed in Table 1. Another MAVA-like antenna was constructed on the other side of the substrate. It is fed through a length and breadth of L\({}_{\text{f}}\) and W\({}_{\text{f}}\), respectively, of an exponential transmission line (an arrangement of an up-front feed line and a quarter of circular disc with a radius of \(r_{1}=4.15\) mm). After optimizing both antennas to gain the mandatory working bands, they were combined to produce an antenna with two operational modes (Ant 1: Figure 6a) and (Ant 2: Figure 6b) able of functioning both horizontally and vertically polarization UWB-MIMO antenna for lower and higher 5G, Ka and Ku bands, and X-band communication applications. Adding the curve with radius r\({}_{2}\) and width W\({}_{1}\) added a new resonance frequency and decreased the fringing field, although also somewhat moved the band to the higher band. Around 15 GHz, that similarly enhanced impedance matching. To decrease the degrading radiations and improve the antenna's radiation efficiency, the patch in the first antenna is cut adjacent at the edges of the substrate (the cut length is L\({}_{\text{g1}}\)). By examining the surface current distribution at the required frequencies, the gaps impact, the tapered angle, and the optimum sizes were studied. Knowing how to convert a stop band to a passband is also beneficial. Figure 2 depicts the surface current density (SCD) in targeted working resonances (3.8 GHz, 5.2 GHz, 8 GHz, 15 GHz, 22 GHz, and 28 GHz). At different frequencies, the amount of the SCD on the ground close to the patch on the other side, the transmission line, and the two cross-curves are the strongest for Ant 1.