# Ultra-Wideband Compact Fractal Antenna for WiMAX, WLAN, C and X Band Applications
## 2 Antenna Design
### Design Evolution Methodology  
The evolution of the fractal patch design is shown in Figure 2a-f. The initiator was presented by the fundamental circular antenna with a partial ground with resonant frequencies at 5.87 GHz and 6.35 GHz. The second step was to remove four squares with 3.33 mm edges from the feed line side, to disturb the current distribution of the antenna, create new resonant frequencies and generate a wider bandwidth (of 2.15 GHz). The size of the squares was determined to be 3.33 mm, based on simulation results and optimization processes aimed at achieving the desired performance parameters for the antenna design. Four more rectangular sections \begin{table}
\begin{tabular}{l c c c c c c c c c c} \hline \hline
**Parameter** & **Ws** & **Ls** & **Wg** & **Eg** & **R** & **T** & **P** & **Lg** & **Lg1** & **WL** \\ \hline Values(mm) & 34 & 40 & 2.6 & 1 & 12 & 3.33 & 1 & 15 & 12.25 & 17 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Ultimate size of fractal antenna proposed. Figure 1: (**a**) The front plane, and (**b**) the ground plane of the suggested antenna. Figure 2: Steps taken to achieve the ultimate design of the suggested antenna. were cut from the patch in the same size as that cut in the third iteration. The choice of four squares was determined through a trial-and-error approach during the iterative procedure, where various configurations were tested to improve the antenna's performance. This iteration offers four resonance frequencies of 0.29 [1.84, 2.13] GHz, 1.06 [4.49, 5.55] GHz, 0.39 [5.98, 6.37] GHz, and 2.09 [8.95, 11.04] GHz  
In the fourth iteration, the ground was modified by a rectangular slit with a 1 mm thickness, and this modification offers two operating bands, [2.43, 3.54] GHz and [7.45, 10.79] GHz. In the proposed antenna, a \"L\" shape is welded on the partial ground that gives two wide bands with impedances of 1.84 [2.26, 4.10] GHz and 3.9 [6.10, 10] GHz, as shown in Figure 3.  
This patch is applicable to the WLAN, C, and X bands, Bluetooth, and WiMAX. To clarify, the proposed antenna was designed to operate within the frequency ranges typically associated with C and X bands. While the frequency range of 2.30 GHz to 4.10 GHz technically falls under the S-Band, it is sometimes referred to as the lower C-Band (3.7-3.98 GHz). Additionally, the frequency range of 6.10 GHz to 10.0 GHz partially falls within the IEEE-defined C-Band range and is also considered part of the X-Band. Therefore, while the antenna may not cover the entire spectrum of C and X bands, it is compatible with many applications within these frequency ranges. It is concluded that during the antenna's evolution, the S-parameter curves are improved. The antenna evolution results are presented in Table 2. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Iterations** & **Frequency Number** & \begin{tabular}{c} **Loss Return** \\ **dB** \\ \end{tabular} & \
\begin{tabular}{c} **Bandwidth** \\ **GHZ** \\ \end{tabular} \\ \hline The initiator & 1 & \(-\)13.2 & 0.48 [5.87, 6.35] \\ \hline Iteration 1 & 1 & \(-\)20.43 & 2.46 [2.9, 5.36] \\ \hline Iteration 2 & 1 & \(-\)32.64 & 2.15 [2.69, 4.84] \\ \hline Iteration 3 & 4 & \(-\)13.12 & 0.29 [1.84, 2.13] \\  & & \(-\)13.83 & 1.06 [4.49, 5.55] \\ Iteration 3 & 4 & \(-\)11.47 & 0.39 [5.98, 6.37] \\  & & \(-\)21.9 & 2.09 [8.95, 11.04] \\ \hline Iteration 4 & 2 & \(-\)18 & 1.11 [2.43, 3.54] \\  & & \(-\)16.31 & 3.34 [7.45, 10.79] \\ \hline \hline \end{tabular}
\begin{tabular}{c c c} \hline \hline  & & \(-\)27.08 & 1.84 [2.26, 4.10] \\ The proposed antenna & 4 & \(-\)26.60 & 2.38 \\  & & \(-\)16.28 & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Antenna frequency number, loss return, and bandwidth for each iteration. Figure 3: Comparison of the S11 at different design stages. The suggested antenna has was the subject of comprehensive study to optimize its design and it was found that its current design offers the best bandwidth performance.