# A Wideband Eight-Element Antenna with High Isolation for 5G New-Radio Applications
## 3 Measurement Results and Discussion  
The photos of the produced antenna and the measurement setup are demonstrated in Figure 10. The S-parameters of the antenna are measured by the PNA N5224A network analyzer. The comparison of the measurement and the simulation is presented in Figures 11 and 12. It shows that the \(-10\) dB impendence band is 3.3-5.45 GHz. There is some deviation between the emulation and measurement results, which is mainly owing to the manufacturing error and the manual welding of the SMA connector. The values of the measurement results of the transmission coefficient surpass \(-15\) dB in 3.3-5 GHz. Figure 11: The measurement and simulation results of the reflection coefficients of the antenna. Figure 10: The portraitaiture of setup for measurements: (**a**) fabricated antenna; (**b**) vector network analyzer; (**c**) anechoic chamber. As shown in Figure 13, the results of measurement and simulation normalized radiation polarization of the displayed antenna at 3.4 GHz, and 4.9 GHz are proposed. A solid black line and a dotted green line represent the co-polarization and cross-polarization of measurement results, respectively. In addition, a red solid line and a dotted blue line express the co-polarization and cross-polarization of simulated results, respectively. The welding effect of the SMA connector may cause errors in the results of measurement and simulation. In Figure 14, the measurement and simulation results of peak gain and radiating efficiency of the presented antenna are displayed. The median peak gain is about 3.5 dBi, and it can be seen that the curves of radiation efficiency and peak gain have similar trends. Moreover, the measured and simulated efficiency are higher than 75% in the desired wideband. Calculated ECC and diversity gain (DG) are indicators to define the coupling effects and diversity of MIMO antenna systems. The calculated ECC can be expressed by far radiation field as Equation (1) [4]:  
\[\text{ECC}=\frac{\left|\iint_{4\pi}\left[\overset{\rightarrow}{\text{F}_{1}}( \theta,\varnothing)*\overset{\rightarrow}{\text{F}_{2}}(\theta,\varnothing) \right]\text{d}\Omega\right|}{\iint_{4\pi}\left|\overset{\rightarrow}{\text{F}_ {1}}(\theta,\varnothing)\right|^{2}\text{d}\Omega\ \iint_{4\pi}\left|\overset{ \rightarrow}{\text{F}_{1}}(\theta,\varnothing)\right|^{2}\text{d}\Omega} \tag{1}\]  
The DG is calculated on the basis of Equation (2) [21]:  
\[\text{DG}=10\ \times\sqrt{1-\left|\text{ECC}\right|^{2}} \tag{2}\]  
In Figure 15, the computed ECC and DG are presented, which are lower than 0.005 and higher than 9.99 dB in the desired wideband, respectively. In the case of an ideal antenna system with a total antenna efficiency of 100% and zero correlation between antennas, the multiplexing efficiency (ME) represents the loss of power in the archetype antenna system when it is related to a specified capacity. The ME is presented in Equation (3) [21]:  
\[\text{ME}=\sqrt{\eta_{1}\eta_{2}\left(1-\left|ECC\right|^{2}\right)} \tag{3}\]  
Figure 12: The measurement and simulation results of transmission coefficients of the presented antenna. Figure 14: Measured peak gain and total efficiency of the designed antenna. Figure 13: Measured and simulated 2D radiation charts of (**a**) E-plane at 3.4 GHz; (**b**) H-plane at 3.4 GHz; (**c**) E-plane at 4.9 GHz; (**d**) H-plane at 4.9 GHz. Channel capacity loss (CCL) indicates the rate of information transmitted within a communication channel without data loss. The values of CCL can be calculated by Equations (4)-(7) [9]:  
\[C_{loss}=-\text{log}_{2}\left(\psi^{R}\right) \tag{4}\]  
\[\psi^{R}= \begin{bmatrix}\rho_{ii}&\rho_{\bar{y}}\\ \rho_{\bar{y}i}&\rho_{\bar{y}j}\end{bmatrix}