# Ultra-Wideband Compact Fractal Antenna for WiMAX, WLAN, C and X Band Applications
## 3 Results and Discussion  
The antenna was designed and optimized using the HFSS software 17.2, which is based on the finite element approach (FEM). An FR4 substrate of the optimal size of 40 \(\times\) 34 mm\({}^{2}\) was used to fabricate the suggested fractal antenna to validate the simulation results. Figure 8 shows the top and bottom views of a fabricated antenna. Using a vector network analyzer, the suggested antenna reflection coefficient was measured. Figure 9 displays the comparison between the simulated and measured reflection coefficients of the suggested broadband antenna. The comparison of these results shows that there is good agreement and confirms the wideband operation property. A slight difference is noticed in the higher frequencies; this may be due to the circumstances of  
Figure 8: Front and rear face of the fabricated antenna. Figure 7: Surface current distribution at (**a**) 2.8 GHz, (**b**) 3.51 GHz, (**c**) 6.53 GHz, and (**d**) 9.37 GHz. manufacturing and measurement. In the Figure 9, a correspondence can be found between the simulated and measured results in the first band, [2.3-4.10] GHz. On the other hand, in the second band, a slight improvement can be observed in the measured results in the high frequencies. The proposed prototype antenna covers the range of frequencies from 2.26 to 4.10 GHz and from 6.10 to 10 GHz with an impedance bandwidth of 1.84 and 3.90 GHz successively, and with reflection coefficients of \(-\)28.38 dB, \(-\)27.62 dB, \(-\)21.94 dB, and \(-\)17.45 dB, respectively. The suggested antenna matches the bandwidth requirements of several wireless protocols, such as WiMAX (2.5-2.69, 3.3-3.8, and 5.25-5.825 GHz), WLAN (2.4-2.484 and 5.15-5.825 GHz), C band (6-8 GHz), and X band (8-10 GHz). An anechoic chamber, such as that seen in Figure 10, was used to measure the maximum gain, efficiency, and radiation pattern of the proposed antenna. The peak gain of an antenna depends on several factors, including its size, shape, and radiation pattern. It is an important parameter in the design of antennas, as it determines the antenna's ability to transmit or receive signals in a specific direction. The higher the peak gain of an antenna, the stronger its signal will be in the desired direction, which is particularly important in applications such as satellite communications, radar applications, and wireless networks. Figure 11 displays the comparison between the measured and simulated peak gain results of the suggested antenna for the frequency range of 2 to 10 GHz. The antenna provides impressive results, with a maximum simulated peak gain of 9.2 dB at the frequency of 9.3 GHz, whereas the maximum measured is 9 dB at the frequency of 9.5 GHz. The comparison between the measured and simulated radiation efficiency of the antenna is presented in Figure 12. Radiation efficiency is a measure of the ability of an antenna to convert the electrical power that is supplied to it into electromagnetic radiation that propagates through free space. It is defined as the ratio of the power radiated by the antenna to the total input power supplied to it. In other words, radiation efficiency measures how effectively an antenna is able to convert the electrical energy it receives into useful radiation while minimizing the energy lost as heat or stored in the antenna structure. The radiation efficiency of an antenna is influenced by several factors, such as the antenna's size, shape, material properties, and the presence of nearby objects that can reflect or absorb the radiated energy. The proposed antenna can reach a simulated radiation efficiency of 99% in the operating band. In addition, the radiation efficiency measured reached 92% at 2.3 GHz. The modest discrepancy noted between the simulation and measurement results may have been caused by ambient conditions, manufacturing tolerances, losses at the SMA connector, and impurities in the substrate. However, the results clearly demonstrate good agreement between the simulation and measurement results despite these factors.