## 4 Discussion
### Comparison and Analysis of Measurement and Simulation Results  
Figure 9 depicts the values of AR of the MS at different frequencies for two kinds of LP waves in \(x\) and \(y\) directions with the addition of 8.6 v and 19.8 v DC voltage, corresponding to dielectric constants of \(\varepsilon_{r}=2.8\) and \(\varepsilon_{r}=4.6\), respectively. In Figure 9a, for \(\varepsilon_{r}=2.8\), the AR\(<3\) dB within the frequency ranges of 8.16-8.46 GHz and 9.86-12.48 GHz, with FBWs of 3.61% and 23.46%, respectively. In Figure 9b, for \(\varepsilon_{r}=4.6\), the AR\(<3\) dB for the frequency intervals within 9.78-11.34 GHz, with FBW of 14.77%. Figure 10 presents a comparison of the directivity coefficients of the MS for incident \(x\)- and \(y\)-direction polarization waves, with dielectric constants of \(\varepsilon_{r}=2.8\) and \(\varepsilon_{r}=4.6\). From Figure 10a, it can beseen that the \(x\)-polarized wave is converted to LHCP and RHCP, i.e., DirTotal \(\approx\) DirLHCP, and DirTotal \(\approx\) DirRHCP, respectively, for \(\varepsilon_{r}=2.8\) and the frequency intervals within 8.12-8.52 GHz and 9.76-12.78 GHz, respectively. Figure 10b illustrates the conversion of the \(x\)-polarized wave to RHCP, i.e., DirTotal \(\approx\) DirRHCP, for \(\varepsilon_{r}=4.6\), within the frequency range of 9.8-11.78 GHz. Comparing Figure 10a,c, it can be seen that changing the \(x\)- to a \(y\)-polarized wave alters the direction of the reflected CP wave within the same frequency band and will not have an effect on the frequency band of the LCPC. In Figure 10c, for \(\varepsilon_{r}=2.8\), the \(y\)-polarized wave is converted to RHCP and LHCP for the frequency intervals within 8.12-8.52 GHz and 9.76-12.78 GHz, respectively. In Figure 10d, for \(\varepsilon_{r}=4.6\), the \(y\)-polarized wave is converted to LHCP within the frequency range of 9.8-11.78 GHz. The comparison between the simulation and measured results in Figures 9 and 10 shows good agreement, verifying the validity of the design. However, some deviation remains between the two datasets. This deviation could be attributed to the limitations in the fabrication process of the MS. Specifically, the high temperature used to produce the polyimide during the fabrication of the orientation layer may cause some damage to the layer. Additionally, the distribution of LC molecules during the encapsulation process might be inhomogeneous. Air residues between the layers in the stacked MS structure could also reduce the dielectric constant of the dielectric layer, among other factors, contributing to the observed deviation. Table 2 lists the properties of the proposed MS and compares them with other related works published in the literature.  
Figure 8: (**a**) Physical structure of the layers of the MS prototype and (**b**) DC feed setup. (**c**) Microwave anechoic chamber test setup.  
Figure 10: Comparison of measured and simulated directionality results under \(x\)- and \(y\)-incidence polarized waves: (**a**) directionality (dB) at \(\epsilon_{r}=2.8\), \(8.6\) v, \(x\)-polarized wave, (**b**) \(\epsilon_{r}=4.6\), \(19.8\) v, \(x\)-polarized wave, (**c**) directionality (dB) at \(\epsilon_{r}=2.8\), \(8.6\) v, \(y\)-polarized wave, and (**d**) \(\epsilon_{r}=4.6\), \(19.8\) v, \(y\)-polarized wave.  
Figure 9: Comparison of the measured and simulated AR results under \(x\)- and \(y\)-incidence polarized waves is shown as follows: (**a**) AR (dB) at \(\epsilon_{r}=2.8\), \(8.6\) v \(x\)-polarized wave, and (**b**) \(\epsilon_{r}=4.6\), \(19.8\) v \(y\)-polarized wave.