# Compact Planar Super-Wideband Monopole Antenna with Four Notched Bands
## 2 Antenna Design  
The layout of the proposed quad band-notched SWB antenna is shown in Figure 1. The RT/Duroid 5880 substrate with thickness (\(h\)) of 0.5 mm, relative permittivity (\(\epsilon_{r}\)) of 2.2, and loss tangent (tan \(\delta\)) of 0.0027 is used for the antenna. The proposed antenna consists of a circular radiating patch and a rectangular-shaped ground plane. A tapered microstrip line is integrated with the radiator to feed the antenna. Two inverted U-shaped slots are introduced in the middle portion of the circular patch to notch WLAN and satellite communication-based X-band. Further, a meandered slot and an SRR are introduced in the upper and lower portions of the radiating patch to eliminate Wi-MAX and amateur radio bands, respectively. The enlarged view with design parameters of the meandered slot are shown in Figure 1. The antenna is designed and optimized using a 3-D electromagnetic solver (ANSYS HFSS). The design parameters of the proposed SWB antenna are listed in Table 1. The overall size of the proposed SWB antenna is 18 mm \(\times\) 12 mm \(\times\) 0.5 mm. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **Dimension (mm)** & **Parameter** & **Dimension (mm)** \\ \hline \(L\) & 18 & \(b_{3}\) & 6 \\ \(W\) & 12 & \(b_{4}\) & 9 \\ \(a\) & 5.55 & \(b_{5}\) & 1.55 \\ \(l_{1}\) & 6.15 & \(b_{6}\) & 0.75 \\ \(l_{2}\) & 3.5 & \(b_{7}\) & 1 \\ \(l_{3}\) & 5 & \(b_{8}\) & 2.25 \\ \(l_{4}\) & 4.45 & \(w_{1}\) & 0.3 \\ \(l_{5}\) & 8 & \(w_{2}\) & 0.5 \\ \(l_{6}\) & 2.75 & \(w_{3}\) & 0.3 \\ \(l_{7}\) & 1.25 & \(w_{4}\) & 0.4 \\ \(l_{8}\) & 2.25 & \(w_{5}\) & 0.25 \\ \(l_{9}\) & 3 & \(t_{1}\) & 1.5 \\ \(b_{1}\) & 1.2 & \(t_{2}\) & 0.4 \\ \(b_{2}\) & 3.9 & \(h\) & 0.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Dimensions of the proposed quad band-notched super-wideband (SWB) antenna. Figure 1: Proposed quad band-notched super-wideband (SWB) antenna: (**a**) schematic, (**b**) enlarged view of the meandered slot, (**c**) fabricated prototype. The evolution steps of the proposed SWB antenna are presented in Figure 2. The Antenna-1, shown in Figure 2a, consists of a simple circular patch and a rectangular ground plane. A tapered microstrip line is employed between the radiating patch and the connector to match impedance for wide bandwidth. The characteristic impedance at each section of the tapered microstrip line is transformed from 100 \(\Omega\) to 50 \(\Omega\) by [27]  
\[Z(z)= \begin{cases}Z_{0}e^{2(zL_{t})^{2}\ln\left(Z_{L}/Z_{0}\right)},0\leq z\leq L _{t}/2\\ Z_{0}e^{(4z/L_{t}-2z^{2}/L_{t}^{2}-1)\ln\left(Z_{L}/Z_{0}\right)},L_{t}/2\leq z \leq L_{t}\end{cases}  \tag{1}\]  
where \(L_{t}\) is the length of the taper, and \(Z_{L}\) and \(Z_{0}\) are the corresponding load and characteristic line impedances. The reflection coefficients of the proposed SWB antenna are shown in Figure 3a,b. The Antenna-1 offers (S\({}_{11}\leq-10\) dB) an impedance bandwidth of 2.5-40 GHz. In order to generate band-stop characteristics for the amateur radio band, an SRR is introduced in the lower region of the monopole radiator, as shown in Figure 2b. The length (\(L_{S}\)) of the SRR is calculated as [28,29]  
\[L_{S}=\left(b_{1}+2l_{2}+b_{2}+w_{2}\right)\approx 0.5\lambda_{gi} \tag{2}\]  
\[\lambda_{gi}\ =\frac{c}{f_{ri}}\left(\frac{1}{\sqrt{\varepsilon_{reff}}}\right) \tag{3}\]  
\[\varepsilon_{reff}=\frac{\left(\varepsilon_{r}+1\right)}{2}+\frac{\left( \varepsilon_{r}-1\right)}{2}\left(1+\frac{12h}{0.5\pi a_{eff}}\right)^{-1/2} \tag{4}\]  
\[a_{eff}=a\left\{1+\frac{2h}{\pi\varepsilon_{r}a}\left[\ln\left(\frac{a}{2h} \right)+1.41\varepsilon_{r}+1.77+\frac{h}{a}(0.268\varepsilon_{r}+1.65)\right] \right\}^{1/2} \tag{5}\]  
where \(f_{ri}\) and \(\lambda_{gi}\) are the corresponding center frequency and guided wavelength of the rejected band, \(a\) is the radius of the circular patch, \(h\) is the thickness of the substrate, \(\varepsilon_{reff}\) is the effective relative permittivity of the dielectric substrate, and \(c\) is the velocity of light in free space.