## 3 Results and Discussion
### MIMO Characteristics
Both measured and simulated TARCs for the desired bands are depicted as being less than \(-10\) dB in Figure 17.  
The mean effective gain (MEG) serves as a diversity performance parameter that indicates how much more power the MIMO antenna in a multipath environment can receive than the isotropic antenna [30]. The MEG of the proposed antenna can be calculated using Equation (8) [31]:  
\[ECC_{far-field}=\frac{\left|\iint_{4\pi}\left[\overset{\rightarrow}{R_{i}} \left(\theta,\varphi\right)\times\overset{\rightarrow}{R_{j}}\left(\theta, \varphi\right)\right]\,d\Omega\right|^{2}}{\iint_{4\pi}\left|\overset{ \rightarrow}{R_{i}}\left(\theta,\varphi\right)\right|^{2}d\Omega\,\iint_{4 \pi}\left|\overset{\rightarrow}{R_{j}}\left(\theta,\varphi\right)\right|^{2} d\Omega} \tag{4}\]0  
where M stands for the total number of elements within the MIMO system. The values of \(MEG_{1}\) and \(MEG_{2}\) can be calculated using the following equations [32]:  
\[ECC_{far-field}=\frac{\left|\iint_{4\pi}\left[\overset{\rightarrow}{R_{i}} \left(\theta,\varphi\right)\times\overset{\rightarrow}{R_{j}}\left(\theta, \varphi\right)\right]\,d\Omega\right|^{2}}{\iint_{4\pi}\left|\overset{ \rightarrow}{R_{i}}\left(\theta,\varphi\right)\right|^{2}d\Omega\,\iint_{4 \pi}\left|\overset{\rightarrow}{R_{j}}\left(\theta,\varphi\right)\right|^{2} d\Omega} \tag{4}\]1  
\[ECC_{far-field}=\frac{\left|\iint_{4\pi}\left[\overset{\rightarrow}{R_{i}} \left(\theta,\varphi\right)\times\overset{\rightarrow}{R_{j}}\left(\theta, \varphi\right)\right]\,d\Omega\right|^{2}}{\iint_{4\pi}\left|\overset{ \rightarrow}{R_{i}}\left(\theta,\varphi\right)\right|^{2}d\Omega\,\iint_{4 \pi}\left|\overset{\rightarrow}{R_{j}}\left(\theta,\varphi\right)\right|^{2} d\Omega} \tag{4}\]2  
To achieve enhanced MIMO diversity performance, the MEG values should fall within [33]  
\[ECC_{far-field}=\frac{\left|\iint_{4\pi}\left[\overset{\rightarrow}{R_{i}} \left(\theta,\varphi\right)\times\overset{\rightarrow}{R_{j}}\left(\theta, \varphi\right)\right]\,d\Omega\right|^{2}}{\iint_{4\pi}\left|\overset{ \rightarrow}{R_{i}}\left(\theta,\varphi\right)\right|^{2}d\Omega\,\iint_{4 \pi}\left|\overset{\rightarrow}{R_{j}}\left(\theta,\varphi\right)\right|^{2} d\Omega} \tag{4}\]3  
According to Figure 18, the simulated MEG values change between \(-6.2\) dB and \(-7\) dB in the desired bands, which falls within the acceptable range mentioned above. \[ECC_{far-field}=\frac{\left|\iint_{4\pi}\left[\overset{\rightarrow}{R_{i}} \left(\theta,\varphi\right)\times\overset{\rightarrow}{R_{j}}\left(\theta, \varphi\right)\right]\,d\Omega\right|^{2}}{\iint_{4\pi}\left|\overset{ \rightarrow}{R_{i}}\left(\theta,\varphi\right)\right|^{2}d\Omega\,\iint_{4 \pi}\left|\overset{\rightarrow}{R_{j}}\left(\theta,\varphi\right)\right|^{2} d\Omega} \tag{4}\]4 Simulated and measured CCL of the proposed MIMO antenna. \[ECC_{far-field}=\frac{\left|\iint_{4\pi}\left[\overset{\rightarrow}{R_{i}} \left(\theta,\varphi\right)\times\overset{\rightarrow}{R_{j}}\left(\theta, \varphi\right)\right]\,d\Omega\right|^{2}}{\iint_{4\pi}\left|\overset{ \rightarrow}{R_{i}}\left(\theta,\varphi\right)\right|^{2}d\Omega\,\iint_{4 \pi}\left|\overset{\rightarrow}{R_{j}}\left(\theta,\varphi\right)\right|^{2} d\Omega} \tag{4}\]5 TARC results of the proposed MIMO antenna: (**a**) simulated; (**b**) measured.