## 4 Results and Discussion  
Figure 10a,b shows the fabricated prototype (front and back view) of the proposed antenna and Figure 10c shows the antenna measurement setup arranged inside an anechoic chamber. The simulated results are obtained by using the commercial software CST-MWS which is based on the Finite Integration Technology (FIT). The reflection coefficient (\(S_{11}\)) measurements are performed by using a Rhode & Schwarz ZVL vector network analyzer (VNA). Figure 11a,b shows the simulated and measured return-loss and voltage standing wave ratio (VS.WR) [19] of the proposed dual-band notched antenna. The measured bandwidth covers the full UWB frequency range from 3 GHz to 12 GHz, except for the two notched bands of 4.17-5.33 GHz and 6.5-8.9 GHz. The first notched band covers some portion of the C-band, and the second notched band covers the downlink of the X-band satellite communication systems. The measured three operational frequency covers the range between 3-4.17 GHz, 5.33-6.5 GHz, and 8.9-12 GHz. The simulated result presented in Table 2 closely matches the measured result shown in Figure 11. It can be understood from Figure 11 that there is a slight shift between the simulated and measured results due to the variation in the loss tangent of the FR4 substrate. This frequency shift problem can be solved in the future by using a low-loss Rogers substrate.  
Figure 12a-c shows the simulated and measured RPs of the designed UWB antenna with dual-notch band characteristics and its fabricated prototype. Both E- (yz-plane) and  
Figure 10: Fabricated Prototype of Proposed Antenna (**a**) Top-layer (**b**) Bottom-layer (**c**) Anechoic chamber measurement setup.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **Operational Bands Coverage (GHz)** & **Rejection Bands Coverage (GHz)** \\ \hline \(S=0.65\) mm & 3–4.2, 5.45–6.72, 9.1–12 & 4.2–5.45, 6.72–9.1 \\ \(S=0.9\) mm & 3–4.2, 5.45–6.77, 8.7–12 & 4.2–5.45, 6.77–8.7 \\ \(S=1.15\) mm & 3–4.2, 5.45–  
H-plane (xz-plane) RPs at 3.5 GHz, 6.1 GHz, and 9.25 GHz are demonstrated, respectively. It can be observed from the results that the H-plane RPs are close to omni-directional shape i.e., similar to the one exhibited by a typical monopole antenna, over the UWB antenna bandwidth except for the two notched bands. From Figure 12a, it can be realized that the antenna radiates in all directions with a maximum measured gain of \(\approx\)2.5 dBi at 0\({}^{\circ}\) angle in the E- & H-plane. Similarly, in Figure 12b, the proposed antenna at 6.1 GHz achieved a maximum measured gain of \(\approx\)5 dBi at 15\({}^{\circ}\) angle in the E- & H-plane. The proposed antenna achieved the highest gain at 9.25 GHz, i.e., close to \(\approx\)5.3 dBi at 30\({}^{\circ}\) angle in E- and at 300\({}^{\circ}\) in the H-plane as shown in Figure 12c. The simulated and measured gain at the complete operating bandwidth of the antenna are shown in Figure 13. It can be observed from the results that the simulated results are in good agreement with the measured results within the experimental errors.  
Figure 11: Simulated and measured S-parameter response of the proposed antenna (**a**) Return-loss and (**b**) VS.WR.  
Figure 12: Simulated and measured E- & H-plane RP (**a**) 3.5 GHz (**b**) 6.1 GHz (**c**) 9.25 GHz.