## 5 Fabrication and Testing  
For the fabrication of the flared SBF antenna, we employed the fused deposition modeling (FDM) 3D printing technique to achieve a low-mass design and reduce production cost and time. The flared SBF antenna was fabricated at the University of Manitoba's ECE machine shop using the Anykubic 3D-printer and polylactic acid (PLA) thermoplastic filament. A polishing post-processing step was performed to eliminate the ridges that formed on the antenna surface due to the 3D-printing layer-by-layer process. This was achieved by applying XTC-3D coating, which is a liquid that consists of a resin part and a hardener part that are mixed together. When a thin layer of this resin-based liquid is applied to the inner surface of a 3D-printed prototype, it fills the ridges, smoothens the surface, and hardens into a resistant coating. After the polishing step, the antenna was coated with MG chemical's silver conductive coating, which is required to create a conductive surface. The top and bottom views of the conductive 3D-printed flared SBF antenna are provided in Figure 11.  
Figure 10: Simulated cross-polarization ratio for the flared SBF antenna with: (**a**) PLA lid; (**b**) ABS lid. The fully assembled antenna consisting of the WR-159 waveguide feed, the PLA cover, and the sub-reflector is shown in Figure 12. In the figure, the waveguide port is connected to the first port of the Keysight PNA Network Analyzer (N5224B) to measure the S-parameter. The measured S11 result is compared to the simulated result in Figure 13. There is very close agreement between the patterns of both plots. The fluctuation in the measured results comes mostly from the waveguide feed. The impedance bandwidth of the fabricated antenna was measured to be 53.7% (4.5-7.8), which is less than that of the simulated result (62.2%). The far-field radiation pattern of the antenna was also measured in the anechoic chamber at the University of Manitoba's antenna laboratory. The radiation pattern results of the flared SBF antenna at \(\phi=0^{\circ}\), \(45^{\circ}\), and \(90^{\circ}\) are shown in Figure 14. The simulated peak gain (which considers the 3D-printed materials used) was 16.78 dBi, while the measured peak realized gain was 15.4 dBi, indicating a gain loss of approximately 1.36 dB. For the worst case cross-polarization analysis, the measured result at \(\varphi=45^{\circ}\), was 20.77 dB (15.34(\(-\)5.43)), which is very close in agreement with the simulated result of 20.15 dB (16.78(\(-\)3.37)). While the other radiation characteristics of the fabricated antenna closely match the simulated results, the gain loss was more than anticipated. Figure 11: Top (**left**) and bottom (**right**) views of the fabricated flared SBF antenna. Figure 12: The fully assembled flared SBF antenna connected to the VNA. Figure 14: Measured radiation pattern results for the flared 3D-printed SBF antenna with the PLA lid at (**a**) \(\varphi=0^{\circ}\), (**b**) \(\varphi=45^{\circ}\), and (**c**) \(\varphi=90^{\circ}\). The dashed lines represent the simulated results, while the solid lines represent the measured results. Figure 13: Measured and simulated S11 results of the flared SBF antenna. To determine the source of this error, a piece of foam with a known dielectric constant of 1.05 was used to replace the PLA lid in order to test if the antenna's gain loss was due to the PLA lid, as shown in Figure 15. The thickness of the foam was designed to be the same dimension as the difference in height between the rim and the sub-reflector (Hs \(-\) Hr = 38.181 \(-\) 32.727 = 5.454 mm). To compare with the measured results, further simulation analyses using the foam material were performed on the flared SBF antenna. The measured and simulated results of the flared SBF antenna with the foam lid are shown in Figure 10:0 The measured peak gain increased from 15.4 dBi to 15.7 dBi when compared to that of the results of the antenna with the PLA lid. A gain loss of about 1 dB was experienced compared to the simulated peak gain result of 16.74 dBi.