# Design and Analysis of Dual-Band High-Gain THz Antenna Array for THz Space Applications
## 4 Simulation
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Parameters** & \(L_{1}\) **(nH)** & \(C_{1}\) **(fF)** & \(L_{2}\) **(nH)** & \(C_{2}\) **(fF)** & \(\frac{f_{c1}}{\text{Calculated}}\) & \(f_{c1}\) **ECM** & \(\frac{BW_{1}}{\text{Calculated}}\) & \(BW_{1}\) **ECM** \\  & & & & & & (**GHz**) & **(GHz)** & **(GHz)** \\ \hline Values & 0.5 & 0.1012 & 0.5 & 0.1012 & 0.70831 & 0.7085 & 10 & 10 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: List of parameters for first resonance frequency \(f_{c1}\). \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Parameters** & \(L_{3}\) **(nH)** & \(C_{3}\) **(fF)** & \(L_{4}\) **(nH)** & \(C_{4}\) **(fF)** & \(\frac{f_{c2}}{\text{Calculated}}\) & \(f_{c2}\) **ECM** & \(\frac{BW_{2}}{\text{Calculated}}\) & \(BW_{2}\) **ECM** \\  & & & & & (**GHz**) & **(GHz)** & **(GHz)** & **(GHz)** \\ \hline Values & 0.5025 & 0.0891 & 0.5 & 0.089 & 0.753 & 0.7525 & 10 & 10 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: List of parameters for second resonance frequency \(f_{c2}\). antenna is somewhat moved to 0.698 and 0.758 THz, and providing \(-10\) dB bandwidth of 8.37 and, 6.83 GHz, respectively. The Type C antenna provides resonance at frequencies of 0.714 and 0.7412 THz with a \(-10\) dB band width of 4.71 and 3.13 GHz, respectively. From Figure 8, it can be seen that the operating bandwidth of the Type C antenna for the 0.714 THz frequency fluctuates in the range of 0.711-0.716 THz, while for the 0.741 THz frequency, it varies from 0.739-0.742 THz. In Figure 8, the small variations in the operating bands are compromised to obtain good performance results at a separation distance \(d\) of 533 \(\upmu\)m. However, a dual-band antenna array is still operating in the allocated bands, which are reserved for the mentioned applications. In the case of every antenna array, the order of array and separation distance \(d\) among the radiating elements are very important parameters as they play a very significant role with respect to the operating bands because they define the behavior of the antenna array in terms of return loss. For comparison proposes, the reflection coefficients of Type A, Type B, and Type C antenna arrays are plotted in Figure 8. The parametric analysis of the Type C antenna array on the basis of separation distance \(d\) among the radiating elements is taken into account from 513-553 \(\upmu\)m, as plotted in Figure 9, where the separation distance of 533 \(\upmu\)m provides a better return loss of \(-20\) dB at 0.714 and 0.7412 THz, respectively. Figure 8: Comparison of return loss vs. frequency. Figure 7: Return losses of dual-band Step 4 THz antenna and equivalent circuit model. In Figure 10, the voltage standing wave ratios (VSWRs) of the Type A, Type B, and Type C antennas are analyzed and compared. The Type A antenna provides VSWRs of 1.21 and 1.17 while operating at 0.708 and 0.75225 THz, respectively. Similarly, the Type B antenna provides VSWRs of 1.01 and 1.27 while operating at 0.689 and 0.758 THz, respectively. Similarly, the Type C antenna provides VSWRs of 1.14 and 1.18 while operating at of 0.714 and 0.7412 THz, respectively. These results of the VSWR show strong agreement with the ideal value of 1, which is considered a reasonably matched antenna with the feed line. In Figure 11, the insertion losses of the Type A, Type B, and Type C antenna arrays are depicted; it is clear that the Type C antenna has low insertion losses of 0.021 and 0.05 dB compared to the Type A and B antennas. In Figure 12, the dielectric losses per millimeter are depicted for the Type A, Type B, and Type C antennas. The applied voltage for all the antennas is 5 volts, while the value of capacitance C varies with respect to the effective area \(A_{e}\) of the antennas. Therefore, the Type A, Type B, and Type C antennas have different dielectric losses per millimeter, as mentioned in Figure 12.  
Figure 10: Comparison of all types of array antennas on the bases of VSWR. Figure 9: Parametric analysis of Type C antenna array.