## 5 Conclusions  
We demonstrated and verified through measurements after embedding into the rear spoiler of a passenger car a simple, cheap and easy-to-manufacture circularly polarized dual-band nested antenna array covering multiple 5G frequency bands-of-interest. Combining lower and higher spectral ranges foster scale effects across regions with decreasing network density, deploying next-generation mobile services to all regions worldwide. The nested UE antenna array meets promising performance figures for non-terrestrial 5G automotive applications. The n78-band exhibits a measured impedance bandwidth of 160 MHz with a 3-dB axial ratio bandwidth of 100 MHz, as embedded into the rear spoiler. An uplink data rate of 21 Mbit/s is anticipated from the peak realized gain of 9.9 dBi. At the Ka-band, the n257-band was covered with an impedance bandwidth of more than 4 GHz and with a 3-dB axial ratio bandwidth of 1500 MHz. The embedded array offered a peak realized gain of 13.7 dBi, from which an uplink data rate of 6 Mbit/s can be expected. The anticipated data rate values render numerous automotive wireless and Internet-of-Things applications feasible. In future work, we intend to design a common aperture antenna terminal for terrestrial and non-terrestrial 5G mobile communications covering multiple 5G bands, and to adjust the designs towards practical implementation and field testing. U.T., A.K., H.-P.P., M.E.A. and M.A.H., contributed to conceptualization, articulation, original draft preparation, review, and editing of the document. All authors have read and agreed to the published version of the manuscript. The concept of automotive antennas embedded into plastic parts was developed with partial support from the Federal State of Thuringia, Germany, and the European Regional Development Fund (EFRE) under the grant 2015 FE9042; the concept, design, and implementation of the \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Reference** & **Realization** & **Frequency (GHz)** & **Gain (dBi)** & \
\begin{tabular}{c} **3-dB Axial Ratio** \\ **Bandwidth (MHz)** \\ \end{tabular} &
\begin{tabular}{c} **Dimensions** \\ **(mm3)** \\ \end{tabular} \\ \hline
[21] & Slot antenna and DRA & 27.5 & 5.62 & 5000 & \(30\times 35\times 3.254\) \\
[22] & Dual layer stacked patches & 1.6 & 3.3 & 25 & \(70\times 70\times 4.8\) \\  & 2.5 & 4.2 & 20 & \(70\times 70\times 4.8\) \\
[23] & Triple layer patch array & 20.5 & 9.6 & 130 & \(40\times 40\times 0.8\) \\  & 30.5 & 10.9 & 3200 & \\ This work & Plastic-embedded dual & 3.5 & 9.9 & 100 & \\  & layer patch array & 28 & 13.7 & 1500 & \(90\times 90\times 1.25\) \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Performance comparison with published works. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & \multicolumn{2}{c}{**Bare Antenna**} & \multicolumn{2}{c}{**Embedded Antenna**} \\ \cline{2-4}  & **Simulated** & **Measured** & **Measured** \\ \hline Input reflection \(|S_{11}|^{2}\) (dB) & \(-14\) & \(-16\) & \(-14.5\) \\ Realized gain G (dBi) & 15.4 & 14 & 13.7 \\
10-dB bandwidth B\({}_{-10}\) (GHz) & 4 & \(>\)4 & \(>\)4 \\ Radiation efficiency \(\eta\) (\%) & 85 & 60 & 56 \\
3-dB axial ratio bandwidth & 1300 & 1525 & 1500 \\ B\({}_{\text{AR}}\) (GHz) & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Summary of simulated and measured results of bare and embedded n257- band array. NTN array has been funded by the German Space administration (DLR) under the grant 50 RK 2121. The Article Processing Charge was funded by Open Access Publication Fund of the Technische Universitat Ilmenau. **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable. **Data Availability Statement:** Not applicable. **Acknowledgments:** We greatly acknowledge valuable contributions from [PERSON] at TU Ilmenau, from [PERSON] at BMW AG, from Mario Nowack GmbH and from [PERSON] and [PERSON] at Wiegand GmbH. **Conflicts of Interest:** The authors declare no conflict of interest.