# A Jug-Shaped CPW-Fed Ultra-Wideband Printed Monopole Antenna for Wireless Communications Networks
## 2 Antenna Design Analysis
### Different Design Steps  
Figure 2 shows the different design steps of the designed monopole and the S\({}_{11}\) behavior given in Figure 3. In the first step, the basic design consists of a simple rectangular printed monopole radiator excited by a coplanar waveguide (CPW) feedline, as shown in ANT I. Then, in the second step, the simple rectangular radiator is truncated from its upper and lower sides to keep its shape similar to the body of a jug, which helps to keep the S\({}_{11}\) (dB) close to \(-10\) dB, but the antenna only operates at 3.5 GHz and 10.5 GHz. Again, in the third step, a semicircular-shaped patch is introduced in the ANT II, which keeps some portion of the UWB band below \(-10\) dB, but the antenna works from 3.3 GHz to 9 GHz and 9.3 GHz to 12 GHz, as can be seen in ANT III (Figure 3), and this is not a required frequency band. Now, in order to achieve the whole UWB spectrum from 3 GHz to 11 GHz, a C-shaped resonator is introduced in the final step to make the shape similar to a handle of a jug, as shown in ANT IV.  
The design process of the printed monopole antenna is explained as follows: The primary antenna design (ANT I), shown in Figure 3, contains a 50 \(\Omega\) CPW feedline, a jug-shaped monopole, and the ground plane. The printed monopole's width and length are calculated using Equations (1) and (2) [13], as follows:  
\[Wp=\frac{\lambda_{o}}{2(\sqrt{0.5}(\varepsilon_{r}+1)} \tag{1}\]  
Figure 3: S\({}_{11}\) (dB) of the different design steps of the presented UWB antenna shown in Figure 2.  
Figure 2: Design steps of the presented ultra-wideband antenna: (**a**) rectangular printed monopole only (ANT I), (**b**) truncated monopole (ANT II), (**c**) addition of semicircular printed monopole (ANT III), (**d**) presented design (ANT IV).  
where \(\epsilon_{r}\) and \(\lambda_{o}\) are the relative permittivity and the wavelength of the substrate in free space at the operating frequency. The best option of \(Wp\) tends to the perfect impedance matching. The length of the printed monopole can be evaluated by using Equation (2).  
\[Lp=\frac{c_{o}}{2f_{o}\sqrt{\epsilon_{eff}}}-2\Delta L_{p} \tag{2}\]  
where \(c_{o}\), \(\Delta L_{p}\), and \(\epsilon_{eff}\) are the velocity of light, change in the length of the printed monopole due to its fringing effect, and the effective dielectric constant, respectively. The effective relative permittivity can be calculated using Equation (3):  
\[\epsilon_{eff}=\frac{\epsilon_{r}+1}{2}+\frac{\epsilon_{r}-1}{2}(\frac{1}{ \sqrt{1+12\frac{\hbar s}{W_{p}}}}) \tag{3}\]  
where _hsub_ is the height of the substrate. At the end, the fringing effect can be calculated using Equation (4):  
\[\Delta Lp=0.421h_{\mathrm{s}}\frac{(\epsilon_{eff}+0.300)(\frac{W_{p}}{\hbar s} +0.264)}{(\epsilon_{eff}-0.258)(\frac{W_{p}}{\hbar s}+0.813)} \tag{4}\]  
With the placement of \(\epsilon_{r}=4.3\), _hs_ = 1.6 mm in Equations (1)-(4), the initial parameters of the rectangular printed monopole are \(Lp\) = 15 mm and \(Wp\) = 12 mm.  
With a simple rectangular monopole (ANTI), the antenna works only works at 3.5 GHz and 9.8 GHz, as shown in Figure 3. By ANT II, the bandwidth of the antenna is increased but is unable to achieve UWB band. Then, in the third step (ANT III), with the help of the semicircular printed monopole on the top of the truncated printed monopole, the antenna achieves most of the UWB band, as the antenna has achieved band from 3 GHz to 11 GHz.