# Spiral-Resonator-Based Frequency Reconfigurable Antenna Design for Sub-6 GHz Applications
## 3 Results and Discussions  
### Simulation Results  
The proposed antenna structure is simulated with four different configurations to analyze the impact of switch states on operating frequencies and resonance frequencies. The simulation results, presented in Figure 7, show the reflection coefficients of the antenna with and without switches. The figure demonstrates that changing the switch states significantly affects the frequencies at which the antenna operates and resonates.  
Figure 8 illustrates the radiation efficiency parameter of the proposed antenna in different configurations. Radiation efficiency is a crucial metric that indicates system performance, signal strength range, and power efficiency. The results indicate that the proposed antenna, with its compact size, is well-suited for sub-6 GHz applications. This suggests the designed antenna is a strong candidate for such applications. The radiation efficiency of the OFF-ON state is not explicitly provided in Figure 8 due to the influence of spiral resonators on the antenna's non-radiation characteristics, particularly in applications below 6 GHz. The focus of Figure 6 is to illustrate other pertinent states related to the antenna's performance, such as reflection coefficient and bandwidth.  
Figure 7: The reflection-coefficient (S11) of the frequency reconfigurable antenna for each configuration.  
Table 2 provides an overview of the antenna's performance parameters and their corresponding application areas for all configurations. The table further supports the notion that the proposed design holds great promise for sub-6 GHz applications. Its performance metrics highlight its suitability for a wide range of applications within this frequency range.  
By presenting these simulation results and performance parameters, it becomes evident that the proposed antenna design, with its versatility and compact size, offers significant potential for sub-6 GHz applications. These findings strengthen the case for its inclusion in relevant research and development efforts.  
Figure 9 depicts the radiation patterns at the resonance frequencies for three conditions. It is clear from Figure 9 that all radiation patterns have almost omnidirectional patterns in the frequency range of interest. It is also worth mentioning that omnidirectional radiation pattern yields better performance for wireless communication systems to access devices from any direction.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multicolumn{2}{c}{**States**} & \multicolumn{1}{c}{**Operating Frequency**} & \multicolumn{1}{c}{**Resonance**} & \multicolumn{1}{c}{**Radiation**} & \multicolumn{1}{c}{**App.**} \\ \hline
**D1** & **D2** & **Range (GHz)** & **(GHz)** & **(GHz)** & **(GHz)** & **(GHz)** \\ \hline \multicolumn{2}{c}{} & \multicolumn{1}{c}{} & & & & Wi-Fi (IEEE 802.11 a/n/ac) \\  & & & & & Bluetooth (5 GHz) \\ OFF & OFF & 5.15–5.27 & 5.2 & 50\% & \begin{tabular}{c} Point-to-point microwave links \\ Short or medium range radar (automotive radar, industrial sensing, radar-based security systems) \\ \end{tabular} \\ \hline \multirow{2}{*}{ON} & \multirow{2}{*}{OFF} & 2.14–2.17 & 2.15 & 26\% & 3G (UMTS) \\  & & 4.02–4.47 & 4.3 & 87\% & \begin{tabular}{c} wireless backhaul (4G and 5G networks), \\ satellite communication, broadcast systems \\ \end{tabular} \\  & & 5.15–5.53 & 5.3 & 82\% & \
\begin{tabular}{c} WLAN (IEEE 802.11a/n/ac/ax), \\ commercial Wi-Fi \\ \end{tabular} \\ \hline \multirow{2}{*}{ON} & \multirow{2}{*}{ON} & 2.08–2.11 & 2.09 & 27\% & 5G NR (n1 Band), IoT \\  & & 3.13–3.2 & 3.16 & 74\% & \\  & & 4.49–5.2 & 4.8 & 88\% &
\begin{tabular}{c} Wi-Fi access points (5 GHz) \\ Bluetooth (5 GHz) \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table}
Table 2: Performance parameters of frequency reconfigurable antenna for each switch configuration.  
Figure 8: Radiation efficiency of the proposed frequency reconfigurable antenna for each configuration.