Reflectarray element for beam scanning with polarization flexibility

Reflectarray antennas are very attractive notably because of their low loss, planar profile, easy deployment and low cross-polarization, thereby combining the best features of both conventional arrays and parabolic reflectors [1]. The recent improvements in technology platforms for RF dynamic control, notably Micro-ElectroMechanical Systems (MEMS) [2]-[4], allows to implement beam-scanning reflectarrays to be used in different applications, as satellite communication, synthetic aperture radars (SAR), satellite reception from moving vehicles, emergency communications, etc. The main drawback of reflectarrays is their moderated bandwidth, but in recent years much progress has been made in this regard [5]-[6], increasing their potential. Particularly, aperture-coupled elements can compensate the effects of the differential spatial phase delay by the introduction of true-time delay (TTD) lines. On the other hand, depending on the application dual linear polarization (LP) or circular polarization (CP) must be chosen. This contribution proposes a reflectarray element which can allow to electronically control the phase of the reflected field controlling at the same time its polarization if control devices are implemented. This means that the element can be feed by an LP field (V, H or both) or one CP (RHCP or LHCP), while reflecting the field with any polarization, depending on the specific time-dependent requirements [7].