On the printed reflectarray with polarized transformation

The printed reflectarray acting as a planar discrete reflector is attractive for antenna engineers, due to its advantages in simple construction with printed fabrication, and flexible design with beam orientation. However, it has also some shortcomings, such as narrower frequency bandwidth and lower efficiency than the parabolic antenna. The article emphasizes another reflectarray advantage in polarization transformation with some prototype samples, including linear polarization (LP) to either orthogonal linear polarization (x-LP), or right-/left- hand circular polarization (RHCP/LHCP) and vice versa. In addition, a technique for broadening the reflectarray bandwidth is developed. Why does the polarization need to be transformed from one to another? The orthogonal LP-x-LP transformation between the illuminated wave from the feed and the wave reflected by the array is helpful for avoiding (or at least reducing) the blockage effect due to the feed structure. The LP-CP transformation may be used to replace the λ/4-depth polarized grating on the reflector or the λ/2-depth one on the feed. The research progress on the LP-x-LP and LP-CP transformations is discussed.