# Horizontal Polarized DC Grounded Omnidirectional Antenna for UAV Ground Control Station
## 5 Antenna Fabrication and Measurement Result  
An antenna was manufactured using brass for the design validation. This antenna can be assembled using CNC-machined parts or expensive 3D printing. This antenna was built utilizing the first approach. The antenna had a reduced footprint and conformal shape to maintain low air resistance. The simulated and measured antenna test results are discussed in this section. Figure 6a displays an image of the prototype antenna. The input scattering parameter \(\mathrm{S}_{11}\) of the manufactured antenna was measured with Agilent N5242A VNA's help. In Figure 6b, the simulated and measured \(\mathrm{S}_{11}\) are plotted. Measurements were less than \(-10\) dB from 2.5 GHz to 2.8 GHz, which were in good harmony with simulations. The antenna was a reasonably broadband structure (achieved bandwidth of 11.3%).  
Measured and simulated vertical elevation planes and horizontal azimuth planes of the antenna at 2.6 GHz and 2.7 GHz are plotted in Figure 7. Measurements were done in the the compact antenna test range (ATR) of March Microwave Systems B.V., which uses a source antenna that radiates a spherical wavefront and two secondary reflectors to collimate the radiated spherical wavefront into a planar wavefront within the desired test zone where the test antenna is placed and precalibrated standard gain antennas are used to determine the absolute gain of the AUT(antenna under test). The simulated and measured co-polarization (normalized) and cross-polarization (normalized) radiation patterns in the omnidirectional plane (H-plane) are shown in Figure 7a. The 360\({}^{\circ}\) radiation at the horizontal plane helps to maintain complete yaw plane operation. The measured cross-polarization levels in the azimuth plane are more than \(-40\) dB down, which agrees with the simulation. Figure 7b depicts the simulated and measured co-polarization (normalized) radiation patterns in vertical elevation (E-plane). Figure 8a,b shows a measured azimuth gain ripple of \(\pm 0.5\) dB, whereas the azimuth pattern phase ripple is only 10\({}^{\circ}\) peak-to-peak. These were measured at 2.6 GHz and 2.7 GHz, respectively. Both affirm the excellent stability of the antenna pattern.  
In Figure 9a, the measured and simulated azimuth gain ripple are plotted for the entire frequency range for the clear visibility of the gain fluctuations. The maximum peak-to-peak value is 1 dB in the azimuth plane, confirming a good omnidirectionality. Figure 9b illustrates the simulated and measured gain of our antenna. This DC-grounded antenna demonstrated reliable gain within the entire band. These results indicate promising and effective radiation characteristics in the yaw plane, making this antenna an appealing option for GCS applications.  
Figure 6: (**a**) The fabricated prototype antenna. (**b**) Simulated and measured \(\mathrm{S}_{11}\) of the antenna.  
Figure 8: (**a**) Measured gain ripple vs. azimuth angle, (**b**) measured phase angle ripple vs. azimuth angle, at 2.6 GHz and 2.7 GHz, respectively.  
Figure 7: (**a**) Measured and simulated normalized co-polarization and cross-polarization in the omnidirectional plane, or H-plane; top 2.6 GHz; bottom 2.7 GHz. (**b**) Measured and simulated normalized co-polarization in the elevation plane, or E-plane; top 2.6 GHz; bottom 2.7 GHz.