# A Wideband Metal-Only Patch Antenna for CubeSat
## 3 Experimental Results  
_Antenna Fabrication_  
The proposed patch antenna is fabricated and measured to verify the simulation results and the approach. As shown in Figure 12, the proposed antenna is fed by a 50 \(\Omega\) coaxial cable and a feeding pin. For a clear view, the 50 \(\Omega\) feeding point is enlarged. The proposed antenna is soldered on the ground plane via shorting pins. Figure 13 shows the measured and simulated reflection coefficients of the proposed antenna. We see that the measured data generally agree well with the simulated results. The discrepancy between the measured and simulated results at 1.82 GHz is caused by the soldering error and the fabrication inaccuracies. The proposed metal-only patch antenna achieves a measured \(|S_{11}|<-10\) dB bandwidth of 1.6-2.7 GHz (44.9%) and a small reflection coefficient of \(-24.4\) dB at 2.45 GHz. The inset of Figure 14 shows the test setup inside the far-field anechoic chamber located at the University of Wollongong. Our proposed patch antenna is considered as the antenna under test (AUT) and was positioned on a low reflective test turntable. Moreover, the broadband horn antenna was used as a transmitter and the AUT was used as a receiver. The measurements distance between the transmitter and the AUT was set to 3 m to ensure  
Figure 12: Fabricated prototype of the proposed patch antenna. (**a**) Top view and (**b**) bottom view. Figure 13: Simulated and measured reflection coefficient of the proposed antenna. the AUT lied in the far-field radiation zone during the experiment. We connected the AUT and the horn antenna to port one and port two of the Vector Network Analyzer (VNA), respectively. The test setup was calibrated with a Keysight 85519A 50-\(\Omega\) calibration kit and a characterized female SMA to male N-connector adapter. We set the VNA to transmit at 2.45 GHz with an output power of 0 dBm. The S\({}_{12}\) quantity was then observed to obtain the received power on port one ratioed to 0 dBm for the principal E and H planes. Finally, the VNA was interfaced with MATLAB to plot the measured radiation pattern for 2.45 GHz. Figure 14 depicts the measured and simulated radiation patterns of the proposed antenna in E-plane (x-z-plane) and H-plane (y-z-plane). The measured and simulated results are in good agreement. We see that in x-z-plane, the level of cross-polarization is higher than the cross-polarization in y-z-plane. This is because the use of shorting pins and the feed location generates higher order modes by introducing asymmetry of the antenna's structure and consequently generates the cross-polarized radiation patterns. The proposed antenna achieves a maximum gain of 8.5 dBi with a \(-30^{\circ}\) tilt off broadside in the radiation pattern. This is because the proposed antenna has an asymmetric structure. Table 2 presents a detailed comparison between the proposed antenna and published patch antenna designs for CubeSat communications. All bandwidths refer to \(\left|\text{S11}\right|<-10\) dB. It can be clearly observed that the proposed antenna has higher gain, significantly wider bandwidth and adequate dimensions to be integrated with a CubeSat. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Ref.** & **Antenna Size (mm)** & **Bandwidth \(\left|\text{S}_{\text{11}}\right|<-10\) dB (\%)** & **Gain (dBi)** \\ \hline
[10] & \(100\times 100\) & 2.56 & 7.2 \\
[9] & \(24.1\times 24.1\) & 1.45 & 4.8 \\
[26] & \(110\times 110\) & 9.77 & 5.4 \\
[27] & \(100\times 100\) & 35 & 4 \\
[28] & \(83\times 83\) & 13 & 3.5 \\
[29] & \(80\times 180\) & 11 & 5.2 \\
**This work** & \(100\times 100\) & 44.9 & 8.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Comparison of the proposed antenna with previous S-band patch antenna designs. Figure 14: Measured and simulated radiation patterns in (top) x-z-plane (E-plane) and (bottom) y-z-plane (H-plane) at 2.45 GHz (inset: antenna under measurement).