# Design and Analysis of Dual-Band High-Gain THz Antenna Array for THz Space Applications
## 4 Simulation  
For multiple applications, such as radio astronomy, spectroscopy, free space satellite communication, and space research, the proposed dual-band 4 \(\times\) 1 novel shape THz antenna array is suggested, which operates at 0.714 and 0.7412 THz, respectively. The operational features of the presented antenna are inspected in the frequency range 0.675 to 0.775 THz by utilizing the finite integration technique (FIT) [41]. The details about design and simulation are listed in Table 3. The simulation results of the antenna models are discussed in terms of return loss, gain, directivity, impedance, band width (BW), and radiation efficiency in the mentioned frequency band. In first section, the return losses of all the steps are discussed, as shown in Figure 5, which are useful for the proposed novel shape antenna design analysis. In the second section, the return losses and voltage standing wave ratio (VSWR) of the Type A, Type B, and Type C antenna arrays are discussed in Figures 6-10. The third section deals with the study of Type A, Type B, and Type C antenna array 2D radiation polar plots, and it is discussed in Figure 13. Similarly, the fourth section presents the far-field radiation patterns of all types of antenna arrays, such as Type A, Type B, and Type C as shown in Figure 14. The final fifth section presents the gain (dB) and radiation efficiency (%) verses frequency (THz) graphs of all types antenna arrays, including Type A, Type B, and Type C as shown Figure 15.  
As mentioned earlier, Figure 5 analyzes the return losses verses frequency graphs for single-element antennas, such as the Step 1, 2, 3, and 4 antennas, which resonate at 0.714, 0.698, and 0.702 THz, respectively. Step 4 is dual-band antenna resonating at 0.714 and 0.7412 THz with \(-\)10 dB bandwidths of 4.71 and 3.13 GHz, respectively. It is observed in Figure 5 that the Step 1 antenna resonates at 0.6985 THz, providing a \(-\)10 dB bandwidth of 8.67 GHz. The resonance frequency of Step 2 antenna is slightly shifted toward right side, and it operates at 0.7025 THz and provides a \(-\)10 dB bandwidth of 15.44 GHz. Similarly, the resonance frequency of the Step 3 antenna is further slightly shifted toward the right side, and it operates at 0.711 THz and provides a \(-\)10 dB bandwidth of 11.73 GHz. Moreover, the Step 4 antenna is a dual-band antenna; it operates at 0.7085 and 0.75225 THz with \(-\)10 dB bandwidths of 9.08 and 6.34 GHz, respectively. Figure 7 provides comparable information about the impedance matching of the Step 4 antenna and the equivalent circuit model, while Figure 6 presents the equivalent circuit model of the dual-band THz antenna and feed line as mentioned in Step 4. The equivalent circuit of the \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Type** & **Parameter** & **Unit** & **Value** \\ \hline Polyimide substrate & Relative permittivity & Unit less & 3.5 \\  & Frequency Range & THz & 0.675 to 0.775 \\  & Mesh Type for Time Domain solver & Unit less & Hexahedral \\  & Impedance & On & 50 \\  & Density (rho) & Kg/m\({}^{3}\) & 1400 \\  & Yong Modulus & GPa & 2.5 \\ Simulation Solver & Solver Type & Unit less & Finite Integration Technique \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Investigation of presented antenna models by simulation parameters..  
proposed dual-band antenna comprises a radiating patch and a feed line; the radiating patch is represented by one resistor (\(R\)), two inductors (\(L\)), and one capacitor (\(C\)). All of them are connected in parallel.