# Metamaterial Integrated Folded Dipole Antenna with Low SAR for 4G, 5G and NB-IoT Applications
## 3 Antenna Design and Result Analysis
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multicolumn{2}{c}{**Controlling Elements in mm**} & \multicolumn{5}{c}{**Case**} \\ \cline{2-7}  & & **1** & **2** & **3** & **4** & **5** \\ \hline \multirow{2}{*}{High frequency elements} & L\({}_{4}\) & 10 & 8 & 7 & 4.5 & 7.5 \\ \cline{2-7}  & W\({}_{4}\) & 1 & 5 & 6 & 9 & 10 \\ \hline \multirow{4}{*}{Middle frequency elements} & L\({}_{5}\) & 25 & 20 & 18 & 17 & 16 \\ \cline{2-7}  & W\({}_{5}\) & 1 & 2 & 2.5 & 2.5 & 3 \\ \cline{2-7}  & L\({}_{2}\) & 20 & 21 & 22 & 23 & 23 \\ \cline{2-7}  & W\({}_{2}\) & 1 & 3 & 5 & 6 & 7 \\ \hline \multirow{4}{*}{Low frequency elements} & L\({}_{1}\) & 31 & 29 & 27 & 27 & 26 \\ \cline{2-7}  & W\({}_{1}\) & 1 & 2 & 3.5 & 4 & 4.5 \\ \cline{2-7}  & L\({}_{3}\) & 30 & 30 & 27 & 27 & 26 \\ \cline{2-7}  & W\({}_{3}\) & 1 & 3 & 4 & 5 & 5.5 \\ \hline \multirow{2}{*}{
\begin{tabular}{c} BW \\ \(f_{b}-f_{bl}\) \\ (GHz) \\ \end{tabular} } & 1.7 to 2.05 & 1.7 to 2.12 & 1.7 to 2.5 & 1.85 to 2.12 and 2.75 to 3.6 & 1.85 to 3.8 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Controlling elements of variable width dipole. Figure 9: Front view of antenna design. A notch at 2.7 GHz is observed in the operational bandwidth by feeding element 5 from both ends via element 2 apart from the conventional connection with element 4. The dimensions and the scattering plot for the folded dipole antenna are represented as case 5. The folded dipole resonates from 1.85 to 3.8 GHz with a bandwidth of 1.95 GHz and 69.02 of bandwidth percentage with two peaks of resonance. The folded design is capable of covering the 5G NR n78, NR-IoT bands B1, B2 and B25, and eleven TDD LTE bands from 33 to 43. The minimum scattering loss observed for the design is \(-42\) dB with 50.22 \(\Omega\) of impedance; therefore, the antenna can be fed directly with a 50 \(\Omega\) line without the need for a separate cascaded impedance matching circuit. Figures 11 and 12 represent the radiation pattern for all the covered bands in XY and YZ planes. A figure-of-eight pattern is observed in the azimuth plane for low and middle frequencies, whereas the pattern approximates the figure-of-eight shape in high frequencies with less emission below the y axis. Thus, the ground plane contributes to radiation in the low and middle frequency bands and acts as a reflector for high frequency bands. By comparison, omnidirectional radiations are observed in the polar plane. The ground is observed to be a reflector at low wavelength and a radiator at high wavelength, which results in less radiation at 90 polar for increasing frequencies. Therefore, the antenna approximately radiates in a doughnut pattern. Figure 11: Antenna radiation pattern in the azimuth plane. Figure 10: Back view of antenna design. The gain values for the folded dipole antenna for different bands are detailed in Table 2. The gain observed for the low frequency LTE band is between 2.735 and 2.989 dB and that for middle frequency LTE bands is between 3.150 and 3.677 dB. For high frequency LTE and NR bands, the gain is between 4.757 and 4.926 dB. It is evident from all the obtained results that the designed antenna can resonate for 4G/5G/IoT bands with sufficient performance parameters. The prototype was fabricated and tested to validate the performance of the antenna, and the photograph of the fabricated prototype is shown in Figure 13. Experimental results of the designed antenna were measured using Anritsu Vector Network Analyzer (VNA), model no. MS46322A. The measured and simulated S11 parameters of the fabricated an