# A Compact Dual-Band Microstrip Patch Antenna for C- and X- and Ku-Band Applications +
## 3 Results  
S-parameters, also known as dispersion parameters, are a set of complex numbers that describe the behavior of an antenna in a microwave circuit. There are four S-parameters, S11, S12, S21, and S22, which represent the reflection coefficient, forward transfer coefficient, reverse transfer coefficient, and load impedance matching factor.  
In the given scenario, the antenna operates in the C- and X- and Ku-bands and has an operating frequency of 7.6 GHz and 12 GHz, as shown in Figure 2. The bandwidth of the antenna is 840 MHz at the operating frequency of 7.6 GHz, and the bandwidth is 890 MHz at the operating frequency of 12 GHz. The return loss of the antenna is measured at  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Parameter** & **Value (mm)** & **Parameter** & **Value (mm)** & **Parameter** & **Value (mm)** \\ \hline W & 16 & S & 5.87 & L & 16 \\ Wf & 0.6 & R2 & 2 & Lf & 4.21 \\ R & 5 & W1 & 0.21 & R & 1.1 \\ L1 & 2.68 & R1 & 2.3 & & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Design antenna parameter values.  
Figure 1: Antenna design: (a) step 1, (b) step 2, (c) step 3, (d) step 4.  
\(-30.25\) dB, representing the amount of energy reflected from the source due to a mismatch between the antenna and the transmission line or load. Return loss assesses power transfer efficiency in the antenna and transmission system. A value of \(-30.25\) dB indicates a good impedance match, with only a small portion of the transmitted energy being reflected. This suggests that the antenna has been matched well to the transmission line, enabling efficient energy transfer and improved signal transmission while minimizing signal loss. Achieving a good impedance match is crucial for maximizing antenna performance by ensuring that most of the transmitted energy is radiated and not wasted as reflected power. A high return loss value demonstrates an efficient operation of the antenna within the given transmission system or load conditions, achieved through minimized reflections and optimized power transfer. VSWR (voltage standing wave ratio) is a measure of the mismatch between the impedance of an antenna and the transmission line to which it is connected [12]. A VSWR of 1:1 means a perfect match, while a higher value means a mismatch.  
In this case, the VSWR of the antenna is given as 0.565 at a frequency of 12 GHz, as shown in Figure 2b. This means that there is a mismatch between the antenna and the transmission line, and the reflected signal has a magnitude of 0.565 times the forward signal. The combined VSWR of the different antennae is shown in Figure 3. Antenna gain is a measure of the antenna's ability to direct or focus radiated energy in a specific direction. It is usually expressed in decibels (dB) relative to an isotropic radiator (a theoretical antenna that radiates equally in all directions) [13]. In this case, we obtained the antenna gain at two different frequencies: 7.13 dB at 7.6 GHz and 8.07 dB at 12 GHz. This means that the antenna has a higher gain at a higher frequency. Also, the gain of the proposed antenna is greater than the previous antenna discussed in this paper.  
Antenna gain is a function of several factors, including the physical dimensions of the antenna, the shape of the antenna, and the frequency of operation. In general, as the frequency of operation increases, antenna gain tends to decrease unless special measures  
Figure 3: (a) Current Distribution (b) E- and H-plane.  
Figure 2: Simulated results: (a) S-parameters (b) VSWR.  
are taken to increase the gain at higher frequencies. The current distribution and E- and H-plane of the proposed antenna are shown in Figure 3a and Figure 3b, respectively.