RHC-Based Systematic Design of a Wide-Angle Periodic Coded THz Reflectarray

A reflectarray designed by Random Hill Climbing (RHC) optimization process is demonstrated and simulated. On the basis of top layer effect on reflection phase and exploiting the relation between phase distribution and the direction of the reflected beam, six pixelated subcells are optimized for two incident angle waves simultaneously. The far field plot shows that for beams of incident angles 19.471° and 41.81° and in the precincts of them the reflectarray deflects the incident waves into reflections close to normal to the reflectarray surface. This shows a proximate independency of incident wave angle for the reflectarray in a certain angular range. The proposed cells provide 342° reflection phase range. Also, the reflection loss of the cell for the incident angles 19.471° and 41.81° are -1.9 dB and -1.4 dB, respectively. The pattern gain and fractional bandwidth for a finite reflectarray of size $300 \lambda \times 150 \lambda$ are reported to be 19.44 dB and $\mathbf{2 5 \%}$ for the incident angle 19.471°, and 19.17 dB and $\mathbf{3 0 \%}$ for the incident angle 41.81°.