# CPW-Fed Transparent Antenna for Vehicle Communications
## 4 Conclusions  
A CPW-fed fully transparent antenna for vehicular communication standards was designed, manufactured, and measured. The crossmatch technique was used for the impedance matching to achieve the target frequencies through parametric simulation. The antenna was designed and fabricated using commercial ITO-coated glass with a sheet resistance of 8 ohms/square. Opposite to other works that also use conductive films with a high sheet resistance, the experimental parameters obtained showed a behavior following the one simulated. Despite the frequency shift in the measured reflection coefficient, the fabricated antenna covers the range of 1.82-2.5 GHz at the lower band and 4.66-11.84 GHz at the upper band for 2.1 GHz and 5.9 GHz requirements, respectively. Those ranges comply with the IEEE 802.11p standard and LTE sub 6 GHz communication bands for vehicular communications applications. The proposed antenna achieves an omnidirectional radiation H-plane patterns. As expected, the peaks gain of the antenna, in the desired frequencies, were negative. Additionally, the proposed antenna presents low radiation efficiency under 15%. These behaviors are due to the sheet resistance of the ITO film, and it can be improved by increasing the thickness of the ITO film, but it would reduce the transparency of the antenna.  
Conceptualization, J.I.T.-F, R.T.-M, J.M.M.-P, M.A.V.-A, E.I.T.-F, M.L.-L, and E.C.-B.; methodology, J.I.T.-F, R.T.-M, and E.C.-B.; software, J.I.T.-F, R.T.-M, M.L.-L., and E.C.-B.; validation, J.I.T.-F, R.T.-M., and E.C.-B.; formal analysis, J.I.T.-F, R.T.-M., J.M.M.-P, E.I.T.-F, M.L.-L, and E.C.-B.; investigation, J.I.T.-F,  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Reference.**} & **Frequencies** & **S11 Min Level** & **Substrate/Conductive** & **Dimensions** & **Match** \\  & **(GHz)** & **(dB)** & **Film** & **(mm)** & **between M** \\  & & & & & **and S of S11 * \\ \hline
[25] & 2.19–2.58 & –13.97 & Sapphire/GZO & \(60\times 10\times 0.375\) & No \\
[29] & 2–6 & –25 & Glass/ITO & \(25\times 25\times 1.1\) & No \\
[30] & 1–7 & \(<\)–15 & Glass/ITO & \(50\times 50\times 1.1\) & No reported \\
[32] & 4.5–7 & –25 & Acetate/ITO & \(50\times 51\times 0.28\) & No \\
[33] & 2.4–2.65 & –15 & C58/IFZO/AgIZTO & \(23.4\times 2\) & Yes \\
[38] & 3.89–5.97 & –24 & PET/AgHT-8 & \(58\times 78\times 0.9\) & Yes \\ This work & 1.8–2.5/4.66–11.84 & –25 & Glass/ITO & \(50\times 17\times 1.1\) & Yes \\ \hline \hline \end{tabular}  
* (M) Measured, (S) Simulated.  
\end{table}
Table 5: Comparative Analysis with Other Transparent Antennas.  
Figure 7: Simulated distribution current at (a) 2.1 GHz and (b) 5.9 GHz.  
R.T.-M., and E.C.-B.; measurements, J.I.T.-F., R.T.-M., and E.C.-B.; data curation, J.I.T.-F., R.T.-M., and E.C.-B.; writing--original draft preparation, J.I.T.-F., R.T.-M., and E.C.-B.; writing--review and editing, J.I.T.-F., R.T.-M., J.M.M.-P., E.I.T.-F., M.L.-L., and E.C.-B.; supervision, R.T.-M. and J.M.M.-P.; project administration, J.I.T.-F., and R.T.-M.; All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
With thanks to the laboratory of characterization of systems based on microwaves at FCE-BUAP where all experimental characterizations were carried out. J.  
The authors declare no conflict of interest.