## 3 Results and Discussion
In another type of result with 2 \(\times\) 1, return loss results were observed as per the standard antenna calculations S11 < 0. The same acceptable results are also observed in 1 \(\times\) 1 geometry. This analysis will generate the 2 \(\times\) 2 antenna structure, where these oscillating effects are reduced and the antenna operates in a wide band. As shown in Figures 2 and 3, some bands generally show minor oscillating effects between 10 and 17.5 THz. In comparison, for the rest of the band, the proposed antenna structure provides an acceptable return loss, with significantly fewer values of cross-port S parameter (S12, S13, S14, S21...) responses. The effect of the radius of the circular patch in return loss is shown in Figure 5. These results are derived for r1 = r2 = r3 = r4 = 2 \(\upmu\)m. The S11 \(<-\)10 dB values are observed in the majority of cases. The cross-polarization gain is reduced, but co-polarization gain is >3 dB at 7.5 THz of the frequency. This can help us to identify the optimized results for the overall structure. The variation in radius of the patch makes the co- and cross-polarization gain better than the same radius patch structure. The calculated gain for the different antenna types is shown in Figure 6. Figures 7-9 show the variation in gain for the different port excitement conditions and polarization angles. In the simulation environment, the port is excited with different conditions: one-port, two-port, three-port, and all-port excitation. In the case of one-port excitation, the other port is considered no feeding, with the condition of lumped port excitation zero. As shown in Figure 6, the other antenna elements have lower surface current density distribution. This surface current density and impedance matching condition generated the overall gain pattern from the antenna, which was different from two- and higher-number port excitations. We observed that the gain pattern lobes depend on the number of the exciting ports. These results can help identify the variation in directivity with maximum gain for the different port excitation conditions. The various gain-forming conditions using different port excitations are varied in surface conductivity and directivity changes in 2D and 3D. In a real-time application, individual ports excited by the matching circuits and the non-excited port can be connected to matched terminator devices. As shown in Table 2, an average of 7.5 dB gain was observed in the majority of the bands for the type 1 antenna. Due to the oscillating effects, the gain is higher in the 11-15 THz range, but return loss is not the standard antenna parameter. Thus, this band can neglect overall antenna operations. The different antenna MIMO analysis parameters such as MEG, CCL, ECC, DG, and TARC have been calculated for the proposed type 1 antenna. The ECC parameter correlates far-field radiation patterns induced at different ports of the MIMO architecture. An ECC of 0.5 or below is required for any MIMO architecture [22; 23]. ECC can be calculated using electric field magnitude, as shown in Equation (1). The ECC of the antenna and \(j\)th components of the system is represented by \(\rho_{ij}\), whilst the solid angle is represented by \(\Omega\). The assessment of ECC based on far-field radiation factors is a time-consuming and complicated process. Another technique for determining ECC using the S parameter approach is described in Equation (2), as published in [24].