# A Dual-Band Modified Franklin mm-Wave Antenna for 5G Wireless Applications
## 4 Results and Discussion  
In the proposed design, the primary array antenna consists of a modified Franklin array structure printed on a substrate, which is of the material Rogers RT/duroid 6010, having a relative permittivity of 10.2 and a loss tangent of 0.0023. The simulation and measurement results for the S\({}_{11}\) parameter vs. frequency of the antenna is depicted in Figure 13. The S\({}_{11}\) result of the proposed antenna is measured using Anritsu 37269 A Vector Network Analyzer. It can be seen from the figure that the resonant frequency occurs for two values of operating frequency; 22.7 and 34.9 GHz in simulation, and at  
Figure 11: Analysis of variation in the length of first type ground cut \(L_{\text{C}}\). Figure 12: Analysis of variation in the length of second type ground cut \(L_{\text{C}}\). 22.8 and 35.3 GHz in measurement. In the simulation, for the first resonant frequency (i.e., 22.7 GHz), a bandwidth (for S\({}_{11}<-10\) dB criteria) of 2.8 GHz (21.5-24.3 GHz) and fractional bandwidth of 12.25% with maximum S\({}_{11}\) of \(-30\) dB is observed, and for the second resonant frequency (i.e., 34.9 GHz), a bandwidth of 2.1 GHz (33.9-36 GHz) and fractional bandwidth of 6% with maximum S\({}_{11}\) of \(-23\) dB is obtained. During measurement, for the first resonant frequency (i.e., 22.8 GHz), a bandwidth of 3 GHz (21.5-24.5 GHz) and fractional bandwidth of 13% with maximum S\({}_{11}\) of \(-32\) dB is observed, and for the second resonant frequency (i.e., 35.3 GHz), a bandwidth of 1.9 GHz (34.3-36.2 GHz) and fractional bandwidth of 5.3% with maximum S\({}_{11}\) of \(-22\) dB is obtained. Figure 13 clearly shows that the proposed structure achieves good impedance matching at both bands and the simulated and measured results are in close agreement. The surface current distribution patterns for the proposed antenna are analyzed in Figure 14 for both resonant frequencies. At 22.7 GHz, the maximum currents can be observed at the second and third arm from the left, while the corner of the ground creates more significant discontinuity to the flow of current at this band, as demonstrated in Figure 14a. At 34.9 GHz, the current leakage is more from the antenna's first and third arm from the left. Simultaneously, the slots in the ground allow more discontinuity in the current flow, thereby increasing the total current length path covering this particular band, as demonstrated in Figure 14b. The 3D total gain pattern for the proposed antenna at both the resonant frequencies is shown in Figure 15. It is observed that the desired configuration of the antenna produces a maximum gain of 7.8 dB for 22.7 GHz and a gain of 9.7 dB for 34.9 GHz. The gains are reasonably good as the bandwidth obtained at this band is relatively wide. Figure 14: _Cont._  
Figure 13: Reflection coefficient vs. frequency of the proposed antenna. The variation of gain with frequency for the bandwidth of operation for the two resonant frequencies is analyzed, as shown in Figure 16. At the first band, i.e., 22.7 GHz, the gain is nonlinear and may be due to the dimension tuning of slots at ground plane to obtain the desired band. However, at the second band, i.e., 34.9 GHz, the gain varies linearly over the entire resonant bandwidth. The variation of radiation efficiency over the entire operating bandwidth for the two operating bands (i.e., 21.5-24.3 GHz, and 33.9-36 GHz) is  
Figure 14: Surface current distribution plots for frequencies (**a**) 22.7 and (**b**) 34.9 GHz. Figure 15: Three-dimensional gain plot for frequencies (**a**) 22.7 GHz (**b**) 34.9 GHz. also depicted in Figure 16c,d, respectively. It can be noticed that the antenna has radiation efficiency greater than 90%, at both the operating bandwidth, thus ensuring effective radiated power. The radiation pattern for the proposed antenna for \(Phi=0^{\circ}\) and \(Phi=90^{\circ}\) is shown in Figure 17. It can be noted that the obtained pattern is directional and stable for both of the dual frequencies.