Figure 3

Design of linear polarization converters at multiple wavelengths. (a) and (b) Maps and contours of the phase difference of \((\Phi _{L_{2}}-\Phi _{L_{1}})/\pi\) against the bar lengths, where \(\Phi _{L_{i}}\) is the absolute phase calculated using the same method shown in Fig. 2b. The configuration is the same as Fig. 2a except the period (a, \(P = {10}\,\text {mm}\); b, \(P = {5}\,\text {mm}\)) and the frequency of interest (at 10 GHz, 15 GHz, and 20 GHz). (c) and (d) Maps of the fitness function F calculated using Eq. 3 for two periods (c, \(P = {10}\,\text {mm}\); d, \(P = {5}\,\text {mm}\)). The red contour lines for the phase difference of \(\pi\) at the frequency of 15 GHz are also marked. (e) The PCR under the y-polarised incidence for cases A and B in c and d. The configuration is the same as Fig. 2c except for the dimensions. In these simulations, the following parameters are used. Case A: \(P = {10}\,\text {mm}\), \(L_{1} = {9.5}\,\text {mm}\), and \(L_{2} = {6}\,\text {mm}\). Case B: \(P = {5}\,\text {mm}\), \(L_{1} = {6.25}\,\text {mm}\), and \(L_{2} = {2.5}\,\text {mm}\). In all cases, the values of h and d are fixed at \({2.5}\,\text {mm}\) and \({0.4}\,\text {mm}\), respectively.