# Compact Broadband Antenna with Vicsek Fractal Slots for WLAN and WiMAX Applications
## 3 Results and Discussion  
The simulation of the suggested antenna was carried out in both CST MICROWAVE STUDIO\({}^{\circled\), which is based on finite integration technology (FIT), and the CADFEKO  
Figure 6: Parametric studies for the variation in the ground plane length \(L_{g}\). Figure 7: Parametric studies for the variation in the Vicsek fractal slot length \(a\). simulator, which uses the method of moments (MoM). The antenna was excited by a waveguide port, and the boundary box had an area of 200 mm \(\times\) 200 mm \(\times\) 200 mm, as shown in Figure 8, while the number of mesh cells was 374,088. To prove that the simulation results are accurate, the suggested broadband antenna was manufactured as depicted in Figure 9. The reflection coefficient S\({}_{11}\) was measured using vector network analyzer E5071C. The variation of the reflection coefficient S\({}_{11}\) of the suggested broadband antenna is illustrated in Figure 10. It is noticed from the measured results that the antenna presents a broadband of 4.22 GHz from 2.48 GHz to 6.7 GHz with two resonant frequencies at 3.6 and 5.3 GHz with reflection coefficients \(-\)41.3 dB and \(-\)57.2 dB, respectively. The designed antenna provides a broadband which covers the WiMAX bands at frequencies 2.3/2.5/3.3/3.5/5/5.5 GHz and the WLAN at frequencies 3.6/2.4-2.5/4.9-5.9 GHz. The simulated surface current distribution of the suggested broadband antenna results acquired by CST MICROWAVE STUDIG(r) at resonant frequencies 3.6 and 5.3 GHz is depicted in Figure 11. It is seen from the figure that the current distribution is concentrated at the inset microstrip feed line, the ground plane and the extremity of the octagonal radiator at 3.6 GHz. Similarly, in the 5.3 GHz frequency, the high current surface is concentrated at the inset feed line, the ground plane. Figure 8: Boundary box of the proposed antenna. Figure 9: Manufactured prototype of the proposed antenna. The measurements of radiation pattern and peak gain of the proposed antenna were made in an anechoic chamber, as shown in Figure 12. In addition, Figure 13 illustrates the measured radiation pattern together with the simulated results acquired by CST MICROWAVE STUDIO(r) and the CADFEKO simulator at resonant frequencies 3.6 and 5.3 GHz. It can be claimed from the figure that the suggested antenna presents a good radiation pattern performance since it achieves an omnidirectional pattern in the H-plane and in the E-plane. The measured peak gain and simulated peak gain obtained by CST MICROWAVE STUDIO(r) and CADFEKO software are illustrated in Figure 14 and the simulated radiation efficiency acquired by CST MWS is depicted in Figure 15. From the figures, it can be revealed that the suggested antenna presents good performance in terms of peak gain and radiation efficiency. The antenna offers considerable gains and radiation efficiencies: 2.78/5.32 dBi and 88.5/84.6% at the operating frequencies 3.6/5.3 GHz, respectively. Figure 11: The simulated surface current distribution of the suggested broadband antenna at (a) 3.6 and (b) 5.3 GHz. Figure 7:0 Measured and simulated S-parameters of the suggested antenna. Figure 7:1 The measurement setup of radiation pattern and gain in an anechoic chamber. Figure 7:2 Two-dimensional radiation patterns: (**a**) E-plane at 3.6 GHz, (**b**) H-plane at 3.6 GHz, (**c**) E-plane at 5.3 GHz, (**d**) H-plane at 5.3 GHz. The simulation results obtained by the CADFEKO and CST solvers, as well as the measurement results, are collected and summarized in Figure 7:3 The impedance bandwidth is 4.15 GHz with two operating frequencies 3.5 and 5.1 GHz for CADFEKO, and the impedance bandwidth is about 4.35 GHz with two resonant frequencies at 3.6 and 5.2 GHz for CST. The measured impedance bandwidth is 4.22 GHz, with two operating frequencies at 3.6 and 5.3 GHz. In addition, when evaluating gain values, the CST result is 2.75 and 5.37 dBi at 3.6 and 5.2 GHz, respectively.