## 2 Material and Method
### Design and Production of the Bow-Tie Microstrip Antenna
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameters** & **Dimensions** & **Dimensions** \\  & **Antenna-2** & **Antenna-3** \\ \hline Patch length PL & 36 mm & 36 mm \\ Base length BL & 32 mm & 32 mm \\ Gap & 4 mm & 4 mm \\ Feedline width & 0.6 mm & 0.6 mm \\ Apex length AL & 5.4 mm & 5.4 mm \\ Substrate length L & 44 mm & 44 mm \\ Substrate width W & 88 mm & 88 mm \\ Aperture length for patch X & 8 mm & 14 mm \\ Aperture width for patch Y & 16 mm & 16 mm \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Bow-tie Antenna-2 and Antenna-3 parameters. Figure 2: The design geometry of Antenna-1. Figure 3: The design geometry of Antenna-2 and Antenna-3 with graphene substrate and different patch dimensions. An SMA connector is connected to the antenna's terminals by heating and softening the graphene; see Figure 4. The connector's positive pin is soldered to the right triangular patch that acts as a positive terminal, and the negative pin is soldered to the left triangular patch. The microwave antennas' design and dimensions were optimized through the simulations using the CST Microwave Studio software. The CAD design was prepared using Tinkercad, and Ultimaker Cura was used to generate gcode for the 3D printer. A commercial Creality Ender 3 Pro printer was utilized to manufacture a 3D printed substrate part from PLA and a conductor part from graphene. The bed and the nozzle temperatures were adjusted as 60 \({}^{\circ}\)C and 205 \({}^{\circ}\)C, respectively for the PLA and 50 \({}^{\circ}\)C and 220 \({}^{\circ}\)C for the graphene. An intermediate printing head speed of 50 mm/s and 30 mm/s was selected for PLA and graphene, respectively. A nozzle with 0.5 mm size is used for the printing. Figure 4: Fabricated bow-tie (**a**) Antenna-1, (**b**) Antenna-2, and (**c**) Antenna-3. Figure 5 shows the manufacturing of the antenna with a commercial 3D printer. Antenna measurements were made in the operating frequency range of 2-20 GHz using a PNA-L Agilent vector network analyzer. Before the measurement was carried out, the VNA was calibrated with a calibration kit with a short circuit, open circuit, and loading apparatus, respectively. After the calibration process, the produced antennas were connected to the VNA, and the return loss parameter and gain measurement results were obtained. In addition, it was also investigated how the changes to be made in antenna geometries, especially in the graphene patch part, can affect the cross-sectional absorption areas. The physical parameters for all antennas are assumed to be \(T\) = 300 K and \(\mu_{e}\) = 0 eV. It is seen that the antennas have resonances close to each other, and there is little difference between them, resulting from different patch structures. As shown in Figure 6, it is clear that the antenna has a large \(\sigma_{abs}\) value, especially in the patch part, which means there is no inference. Figure 5: Creality Ender 3 Pro 3D printer. Figure 6: Absorbing cross-section in (\(\mu\)m)\({}^{2}\) of Antenna-1, Antenna-2, and Antenna-3 with \(T\) = 300 K, \(\mu_{e}\) = 0 eV in CST Microwave Studio.