Broadband polarizer reflectarray antenna in dual-circular polarization for satellite applications in Ka-Band

In this article, a novel design technique for reflectarray antennas is proposed to provide broadband dual-linear to dual-circular polarization (dual-LP to dual-CP) conversion in the entire Ka-band. The design technique implements an in-band optimization routine at the cell level, developed as a general solution for multiresonant reflectarray elements, with design targets defined by the phase of the co-polar reflection coefficients of the cell at three different frequencies. The optimization routine tries to guarantee the focusing of a high gain beam with LP-to-CP conversion at the central frequency, while ensuring the LP-to-CP conversion at the off-center frequencies, which broadens the effective bandwidth (BW) of the polarizer reflectarray antenna. A 20x20 cm reflectarray antenna has been designed considering a dipole-based reflectarray cell. As a result of this in-band optimization, the antenna BW given by an axial ratio (AR) of 1 dB has been quadrupled. The antenna has been manufactured and tested, providing a relative BW of 36.4% for an AR below 1.5 dB, from 28 to 40 GHz.