## 3 Results and Discussion
### Comparison with Existing Designs
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Reference** & **Spectrum (GHz)** & **Bandwidth (GHz)** & **Antenna Elements** & **Antenna Size (mm\({}^{2}\))** & **S\({}_{11}\) (dB)** & **Gain (dBi)** & **Efficacy (\%)** & **SLL (dB)** \\ \hline \multirow{2}{*}{[12]} & 26–29.5 & 1.5 & \multirow{2}{*}{\(1\times 4\) array} & & \(-\)\(-\)\(-\)\(15\) & 12.7 & - & \(-\)\(-\)\(15\) \\ \cline{6-8}  & 36.7–38.7 & 1.9 & & & \(-\)\(-\)\(-\)\(28\) & 14.9 & & \(-\)\(12\) \\ \hline \multirow{2}{*}{[32]} & 25.59–29.63 & 4.04 & \multirow{2}{*}{Single} & \multirow{2}{*}{\(4.62\times 4.49\)} & \(-\)\(19\) & 3.5 & 94 & - \\ \cline{6-8}  & 35.74–43.09 & 7.35 & & & & \(-\)\(26\) & 5 & 95 & - \\ \hline \multirow{2}{*}{[33]} & 27.10–28.80 & 1.7 & \multirow{2}{*}{2} & \multirow{2}{*}{\(4.8\times 2.9\)} & \(-\)\(17\) & 5.3–7.4 & - & \(-\)\(-\)\(-\)\(2\) \\ \cline{6-8}  & 35.20–38.90 & 3.7 & & & & \(-\)\(19\) & 5-6.2 & - & \(-\)\(-\)\(3\) \\ \hline \multirow{2}{*}{[34]} & \(-\)27.50–28.75 & 1.25 & \multirow{2}{*}{Two-Port MIMO} & \multirow{2}{*}{\(7.5\times 8.8\)} & \(-\)\(34.5\) & 6.6 & 98.3 & \(-\)\(-\)\(5\) \\ \cline{6-8}  & \(-\)37.50–38.60 & 1.1 & & & & \(-\)\(27.3\) & 5.86 & 98.5 & \(-\)\(-\)\(3\) \\ \hline \multirow{2}{*}{[35]} & \(-\)27.70–28.40 & 0.7 & \multirow{2}{*}{\(2\times 4\) microstrip, dual-split-ring} & \multirow{2}{*}{\(130\times 53\)} & \(-\)\(-\)\(-\)\(35\) & 4.6 & 55–60 & \(-\)\(-\)\(7\) \\ \cline{6-8}  & \(-\)36.50–39.50 & 3 & & \(-\)\(-\)\(-\)\(24\) & 10.5 & 88–90 & \(-\)\(-\)\(8\) \\ \hline \multirow{2}{*}{[36]} & 27.00–28.40 & 1.4 & \multirow{2}{*}{Single/4} & \multirow{2}{*}{\(1.5\,\lambda 0\times 1.86\,\lambda\)} & \(-\)\(-\)\(-\)\(20\) & 6.73 12.69 & 94 & - \\ \cline{6-8}  & 34.70–40.00 & 5.3 & & & \(-\)\(-\)\(-\)\(22\) & 5.51 & 94 & - \\ \hline \multirow{2}{*}{[37]} & \(-\)25–30 & 5 & \multirow{2}{*}{8} & \multirow{2}{*}{\(16\times 16\)} & \(-\)\(-\)\(-\)\(50\) & 15.6 & - & \(-\)\(-\)\(2\) \\ \cline{6-8}  & & & & & \(-\)\(-\)\(-\)\(50\) & 10 & - & \(-\)\(-\)\(3\) \\ \cline{6-8}  & \(-\)36–42.5 & 6.2 & & & \(-\)\(-\)\(-\)\(40\) & 10 & - & \(-\)\(3\) \\ \hline \multirow{2}{*}{[38]} & 27.60–28.50 & 0.9 & \multirow{2}{*}{5} (Layer) & \multirow{2}{*}{\(15\times 25\)} & \(-\)\(-\)\(28\) & 9 & - & - \\ \cline{6-8}  & 36.90–38.90 & 2 & & & \(-\)\(-\)\(-\)\(22\) & 5.9 & - & - \\ \hline \multirow{2}{*}{[39]} & 25.4–30.84 & 5.44 & \multirow{2}{*}{\(1\times 4\) array} & \multirow{2}{*}{\(6.5\times 23\)} & \(-\)\(-\)\(-\)\(23\) & 11.31 & & \(-\)\(10\) \\ \cline{6-8}  & 38–40 & 2 & & & \(-\)\(-\)\(-\)\(22\) & 11.93 & & \(-\)\(12\) \\ \hline \multirow{2}{*}{Proposed} & 27.63–28.75 & 1.12 & \multirow{2}{*}{Single} & \multirow{2}{*}{\(27\times 33\)} & \(-\)\(53.04\) & 7.82 & 96.02 & \(-\)\(2.2\) \\ \cline{6-8}  & 37.33–38.60 & 1.27 & & & \(-\)\(-\)\(83.65\) & 8.98 & 95.50 & \(-\)\(6.4\) \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Comparison with similar published works. The gain (in dBi) is another crucial parameter that indicates the antenna's ability to direct radio frequency energy. The proposed antenna achieved gains of 7.82 dBi at 28 GHz and 8.98 dBi at 38 GHz, outperforming other designs with lower gains. For instance, the designs reported by [33] exhibit gains ranging from 5.3 dBi to 7.4 dBi, with the proposed single-element antenna delivering comparable performance to multi-element arrays. Efficiency, which measures how effectively an antenna converts input power into radiated energy, is another critical metric. The proposed design demonstrates total efficiencies of 96.02% at 28 GHz and 95.50% at 38 GHz--values that exceed the efficiencies of many comparable designs, where efficiencies range from 80% to 94%. The high efficiency underscores the practical viability of the proposed antenna in advanced communication applications. SLLs in microstrip antennas are considered problematic because they can cause unwanted losses, interference, noise, and reduced directivity, all of which negatively affect antenna performance.