# Recent Developments and State of the Art in Flexible and Conformal Reconfigurable Antennas
## 6 Comparison between Proposed Techniques for Flexible Reconfigurable Antennas  
Table 3 shows a list of materials that are mostly used for flexible and conformal reconfigurable antennas is shown. The table provides the available materials for each fabrication method and their suitability for bending/folding and sustained bending/folding (repeating deformation) for better comparison. For all of frequency, pattern, polarization, or a combination of these characteristics, the reconfigurability methods can be divided into three categories: electrical switch, antenna based on liquid metal/dielectric and Origami-based antennas. Among the presented techniques, antennas based on electric switches employ a much wider range of materials compared to microfluidic and origami-based antennas. Their frequency can be tuned to a couple of states or even a continuous range, whereas limitations exist for the other techniques. However, if actual diodes are employed instead of ideal stubs, a DC-bias and a controlling system are required. Therefore, the flexibility of the antenna will be affected by the integration of the antenna with rigid components. The strong connection between the rigid components and unconventional materials electrically and mechanically is also challenging. For this technique, the nonlinearity effects of diodes on antenna performance should be considered. Furthermore, the efficiency of these types of antennas is usually lower compared to their rigid counterparts. As Table 3 shows, this is due to the lower conductivity of the flexible materials compared to the conventional materials e.g., copper layer with conductivity of \(5.96\times 10^{7}\) S/m. Figure 10: Pattern and frequency-reconfigurable antenna based on liquid crystalline elastomers: (a) straight statues; (b) helix structure with 1.1-turn [113]. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Rotation/Generation**} & \multirow{2}{*}{**Ref. **} & \multirow{2}{*}{**Montial**} & \multirow{2}{*}{**Montial**} & \multirow{2}{*}{**Montial**} & \multirow{2}{*}{**Montial**} & \multirow{2}{*}{**Montial**} & \multirow{2}{*}{**Montial**} & \multirow{2}{*}{**Monality**} & \multirow{2}{*}{**Monality**} & \multirow{2}{*}{**Monality**} & \multirow{2}{*}{**Monality**} & \multirow{2}{*}{**Monality**} & \multirow{2}{*}{**Monality**} & \multirow{2}{*}{**Monality**} & \multirow{2}{*}{**Monality**} & \multirow{2}{*}{**Monality**} & \multirow{2}{*}{**Monality**} & \multirow{2}{*}{**Monality**} & \multirow{2}{*}{**Monality**} & \multirow{2}{*}{**Monality**} & \multirow{2}{*}{**Monality**} & \multirow{2}{*}{**Monality**} \\  & & & & & & & & & & & & & & & & & & & \\ \hline \multirow{9}{*}{[1]} & Spider & Tensile & - & - & - & 1.85 \(\times\) 10\%/Sine & \multirow{9}{*}{Yes} & \multirow{9}{*}{No} & \multirow{9}{*}{1.57} & \multirow{9}{*}{2.58} 0.2 & \multirow{9}{*}{4.8} 17 & \multirow{9}{*}{2.57} & \multirow{9}{*}{15.4} & \multirow{9}{*}{0.59\(\times\)0.51} & \multirow{9}{*}{0.06} \\  & Krat & Tracks & 1.22 & 0.064 & & & & & & & & & & & & \\ \cline{2-17}  & Captions & Conclvency & - & - & - & 0.37 \(\times\) 10\%/Sine & \multirow{9}{*}{Yes} & \multirow{9}{*}{No} & \multirow{9}{*}{1.53} & \multirow{9}{*}{0.53} & \multirow{9}{*}{4.33} & \multirow{9}{*}{0.53} & \multirow{9}{*}{7.1} & \multirow{9}{*}{N/A} & \multirow{9}{*}{N/A} & \multirow{9}{*}{0.58} & \multirow{9}{*}{0.58} \\  & & & & & & & & & & & & & & & & \\ \cline{2-17}  & Grab Grab & Grab & & - & - & 0.37 \(\times\) 10\%/Sine & \multirow{9}{*}{Yes} & \multirow{9}{*}{No} & \multirow{9}{*}{1.53} & \multirow{9}{*}{-} & \multirow{9}{*}{-} & \multirow{9}{*}{0.57} & \multirow{9}{*}{N/A} & \multirow{9}{*}{N/A} & \multirow{9}{*}{0.58} & \multirow{9}{*}{0.58} \\  & Grab & & & & & & & & & & & & & & & \\ \cline{2-17}  & Grab & Grab &In liquid metal-based antennas, power handling is more efficient and highly linear because electric switches are not used. Therefore, this technique is recommended for high-power applications.