# Ultra-Wideband Compact Fractal Antenna for WiMAX, WLAN, C and X Band Applications
## 3 Results and Discussion
The measured radiation efficiency of the suggested antenna  
Figure 9: Comparison of simulated and measured S11. has dips, which could be attributed to simulation assumptions. These assumptions may not reflect the actual conditions under which the antenna is operating, as the simulation may make assumptions about the antenna's surroundings, or about the behavior of the transmitted and received signals, which may differ from the real-world conditions. Figure 13 shows the fractal antenna's radiation pattern as simulated and measured in the E (\(\phi=0^{\circ}\)) and H (\(\phi=90^{\circ}\)) planes, measured inside the anechoic chamber and simulated by the HFSS software. The radiation pattern of an antenna describes how electromagnetic radiation is distributed in space when the antenna is transmitting or receiving a signal. It shows the relative strength of the electromagnetic field in different directions from the antenna. Figure 13a-d displays a great deal of agreement between the simulated and measured results at the resonant frequencies of 2.8 GHz, 3.51 GHz, 6.53 GHz, and 9.37 GHz. The radiation patterns of the suggested antenna exhibit different shapes at different frequencies. At lower frequencies, the radiation patterns show bidirectional radiation with an \"8\" shape in both planes, H and E, indicating the ability to transmit and receive signals in specific directions. As the frequency increases, the radiation pattern becomes quasi-omnidirectional, as demonstrated in Figure 13c,d, meaning that signals are transmitted and received in all directions. These radiation patterns are critical to the practical use of the antenna in various applications. For example, the bidirectional radiation pattern is useful in point-to-point communication systems and radar systems, while the  
Figure 11: Peak gain measurements and simulations for the suggested antenna. Figure 10: Suggested antenna measurement setup inside the anechoic chamber. quasi-ommidirectional pattern is more useful in wireless communication applications where signal coverage in all directions is necessary. Table 3 compares the proposed antenna with other antennas published in the literature in terms of size, substrate type, frequency range, bandwidth, resonance frequency, peak gain, and applications. The mono-bandwidth antenna suggested by [21] has large dimensions of 46.6 \(\times\) 53.4 mm\({}^{2}\) but a small bandwidth. The authors of [22] defined a dual-band antenna with a high gain that reaches 10 dB but that is slightly large in size, has  
Figure 12: Radiation efficiency measurements and simulations for the suggested antenna. Figure 13: 2D radiation pattern at (**a**) 2.8 GHz, (**b**) 3.51 GHz, (**c**) 6.53 GHz, and (**d**) 9.37 GHz. a small bandwidth of 0.55 and 0.2 GHz, and its design is complex to manufacture. The antenna provided by [23] is used in wireless computer networks such as Wi-Fi and C-band networks. It has a large size of with dimensions of 60 \(\times\) 63 mm\({}^{2}\), with narrow bandwidths and a gain that does not exceed 5.79 dB. The one presented by [25] has a large size with a narrow operational band. Additionally, the patch proposed by [26] has big dimensions and poor bandwidth. In [27], the antenna capable of operating at two different frequencies has considerable dimensions of 48 \(\times\) 48 mm\({}^{2}\). However, its bandwidth is limited and does not exceed 250 MHz, and it is suitable for GSM and WiMAX applications. In contrast to the antenna suggested in reference [32], which varies between 1.6-3.8 dB, our designed antenna exhibited a higher gain. According to reference [34], the antenna with the ability to function at two distinct frequencies has large dimensions of 60 \(\times\) 45 mm\({}^{2}\). Nonetheless, its bandwidth is constrained and does not surpass 700 MHz, making it appropriate for applications such as WLAN and WiMAX.