## 3 Result Analysis and Discussion
\[\text{DG}=10\sqrt{1-|\text{ECC}|^{2}} \tag{6}\]  
Figure 6: The radiation pattern of four designed structures. (**a**) DS-1. (**b**) DS-2. (**c**) DS-3. (**d**) DS-4. The broadside directivity is observed in DS-3. Figure 8: Analysis of peak gain for 1-14 GHz. The peak gains of DS-1, DS-2, DS-3, and DS-4 are, correspondingly, 20.44 dB, 12.79 dB, 24.77 dB, and 26.127 dB. Figure 7: Total gain plot of proposed four MIMO antenna structures. The maximum gain is attained for the DS-4 configurations. (**a**) DS-1 represents total gain of 3.63 dB (**b**) DS-2 represents total gain of 4.82 dB (**c**) DS-3 represents total gain of 3.36 dB (**d**) DS-4 represents total gain of 5.23 dB. Figure 9: The E-fields of different structures. (**a**) DS-1 represents E-field of 22.3 V/cm (**b**) DS-2 represents E-field of 18.5 V/cm (**c**) DS-3 represents E-field of 33.3 V/cm (**d**) DS-4 represents E-field of 14.2 V/cm. The diversity gain of the planned four design structures is illustrated in Figure 12. The DG is analyzed over the 1 GHz to 14 GHz range. The DG value almost remains the same, nearly 10 dB for all of the proposed structures. In DS-1, the DG value reduced by around 4.6 dB at 2.3 GHz. Regarding DS-2, the DG value reduced to nearly 6.8 dB at 2.3 GHz. The power received by a diversity antenna relative to that received by an isotropic antenna is the definition of a fading environment. The mean effective gain (MEG) is determined by solving Equation (7). \[ \begin{array}{l}\text{MEG1}=0.5\big{[}1-|S11|^{2}-|S12|^{2}\big{]}\\ \text{MEG2}=0.5\big{[}1-|S12|^{2}-|S22|^{2}\big{]}\\ \text{MEG}=\text{MEG1}/\text{MEG2}\end{array}  \tag{7}\]  
Figure 10: Directivity response for DS-1, DS-2, DS-3, and DS-4. (**a**) DS-1 represents peak directivity of 3.12 dB. (**b**) Normalized directivity of DS-1. (**c**) DS-2 represents peak directivity of 5.16 dB. (**d**) Normalized directivity of DS-2. (**e**) DS-3 represents peak directivity of 3.48 dB. (**f**) Normalized directivity of DS-3. (**g**) DS-4 represents peak directivity of 2.78 dB. (**h**) Normalized directivity of DS-4. A high gain is a need for any respectable MIMO system. The proper MEG response indicates that its diversity performance has been enhanced. Evaluating TARC is the best way to assess radiation performance and frequency response. TARC considers both mutual coupling and accidental signal pairings between ports. The waves that are reflected and incident are used to form Equations (8) and (9), which may be used to obtain the value in terms of the S parameters/  
\[\Gamma_{\mathrm{a}}^{\mathrm{t}}=\frac{\sqrt{\Sigma_{\mathrm{j}}^{\mathrm{M}} \abs{\mathrm{b}}^{2}}}{\sqrt{\Sigma_{\mathrm{j}}^{\mathrm{M}}\abs{\mathrm{a}} ^{2}}} \tag{8}\]  
\[\Gamma_{\mathrm{a}}^{\mathrm{t}}=\sqrt{\frac{\abs{\mathrm{S}_{11}+\mathrm{S}_ {12}\mathrm{e}^{\mathrm{j}\theta}}^{2}+\abs{\mathrm{S}_{21}+\mathrm{S}_{22} \mathrm{e}^{\mathrm{j}\theta}}^{2}}{2}} \tag{9}\]  
The measured and simulated MEG response of the proposed MIMO antenna is represented in Figure 13. It is observed that for all of the proposed design antenna structures, the value is near zero. DS:1 represents the deviation of MEG in the 0.2 to \(-\)0.33 range. The MEG response of DS:2 is within the 0.18 to \(-\)0.37 range. The representative values of DS-3 and DS-4 are near to zero. The authentication of the MEG response is checked by comparing the simulated and measured response. All of the measured MEG responses of all of the structures are within the permitted range. Figure 11: The simulated and measured ECC response of the proposed MIMO antenna structure for the different design structures: DS-1, DS-2, DS-3, and DS-4. Figure 12: Diversity gain of four proposed design structures. (**a**) DG of DS-1. (**b**) DG of DS-2. (**c**) DG of DS-3. (**d**) DG of DS-4. In the above equations, the phase of the incident wave is \(\theta\). bj and aj stand for reflected and incident waves, respectively. Channel capacity loss (CLL) is another crucial factor to consider while assessing the projected antenna's MIMO performance.