# Crescent Microstrip Antenna for LTE-U and 5G Systems
## 8 Conclusions  
Due to the growing demand for mobile data and mobile devices, for 5G applications and applications using broadband LTE internet access, this article proposes a dual-band crescent microstrip antenna. The proposed antenna has two resonant frequencies, the first at 3.52 GHz with a reflection coefficient of \(-31.54\) dB and the second at 5.42 GHz with a reflection coefficient of \(-23.15\) dB. The proposed antenna covers the frequency ranges from 3.4 GHz to 3.8 GHz (operating frequencies of the 5G system) and from 5.150 GHz to 5.850 GHz (operating frequencies of the LTE-U system). The proposed antenna shows efficiency in the range of 80.00-96.68%, and the maximum antenna gain for the resonance frequency of 3.70 GHz is 4.35 dBi. The results also show that its bandwidth is 3.00 GHz (relative bandwidth: 68.18%), which is a very good result, much greater (but not the best) than the results of other works published in the world, e.g., [22; 23; 24; 34], where the operating band of the proposed of antennas is of the order of 0.6 GHz (11.00%). The proposed antenna can serve as a good option for 5G mobile communication and wireless access to local networks that require high bandwidth. The size of the antenna is very compact and its weight is very low, making it suitable for devices where space is the main limitation.  
Conceptualization, R.P.; methodology, M.B. and R.P.; resources, M.B.; validation, M.B.; visualization, R.P. and M.B.; writing--original draft preparation, R.P. and M.B; writing--review and editing, R.P. All authors have read and agreed to the published version of the manuscript.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Performance Measure**} & \multicolumn{2}{c}{**Proposed Antenna**} & \multirow{2}{*}{**Work of [22]**} & \multirow{2}{*}{**Work of [23]**} & \multirow{2}{*}{**Work of [24]**} & \multirow{2}{*}{**Work of [27]**} & \multirow{2}{*}{**Work of [34]**} \\  & & & & & & Simulation & Simulation \\ \hline \multicolumn{2}{c}{Center frequency} & 4.40 GHz & NA & NA & NA & 7.50 GHz & NA \\ \hline BW & S\({}_{11}\leq-10.00\) dB & 3.00 GHz & NA & NA & NA & 9.00 GHz & NA \\ \hline \multicolumn{2}{c}{Center frequency no 1} & 3.52 GHz & 3.50 GHz & 3.60 GHz & 3.60 GHz & NA & 3.8 GHz \\ \hline \multirow{3}{*}{BW} & S\({}_{11}\leq-10.00\) dB & 3.00 GHz & 0.20 GHz & 0.35 GHz & 0.20 GHz & NA & 0.15 GHz \\ \cline{2-6}  & S\({}_{11}\leq-13.97\) dB & 1.02 GHz & 0.15 GHz & 0.30 GHz & NA & NA & 0.10 GHz \\ \cline{2-6}  & S\({}_{11}\leq-19.08\) dB & 0.55 GHz & 0.10 GHz & 0.20 GHz & NA & NA & NA \\ \hline \multicolumn{2}{c}{Center frequency no 2} & 5.37 GHz & 5.50 GHz & 5.45 GHz & 5.50 GHz & NA & 5.25 GHz \\ \hline \multirow{3}{*}{BW} & S\({}_{11}\leq-10.00\) dB & 3.00 GHz & 0.25 GHz & 0.60 GHz & 0.55 GHz & NA & 0.55 GHz \\ \cline{2-6}  & S\({}_{11}\leq-13.97\) dB & 0.70 GHz & 0.15 GHz & 0.45 GHz & 0.40 GHz & NA & 0.45 GHz \\ \cline{2-6}  & S\({}_{11}\leq-19.08\) dB & 0.30 GHz & NA & 0.30 GHz & 0.33 GHz & NA & 0.20 GHz \\ \hline \multicolumn{2}{c}{Relative BW (S\({}_{11}\leq-10.00\) dB)} & 68.18\% & NA & NA & NA & 120\% & NA \\ \hline \multicolumn{2}{c}{Relative BW no 1} & 68.18\% & 5.71\% & 9.72\% & 5.55\% & 120\% & 3.94\% \\ \cline{2-6}  & S\({}_{11}\leq-10.00\) dB & 68.18\% & 4.54\% & 11.00\% & 10.00\% & 120\% & 10.40\% \\ \hline \multicolumn{2}{c}{Max Gain} & 4.35 dBi & 3.10 dBi & NA & 3.00 dBi & NA & 5.8 dBi \\ \hline \end{tabular}
\end{table}
Table 2: Comparison of electrical parameters of the proposed antenna with other antennas, taking into account the bandwidth.  
**Funding:** This work was financed by Military University of Technology under research project UGB-22-741/2022 on \"Electrical parameters measurement of solid materials using the reflection and the free space method in the millimeter band\".  
**Conflicts of Interest:** The authors declare no conflict of interest.