Time Modulated Reflectarray Unit-Cells with Nonreciprocal Polarization Control

This contribution explores nonreciprocal and reconfigurable reflectarray unit-cells with full polarization control based on time-modulated resonators. To this purpose, a unit-cell operating in the X-band is designed to aperture-couple each polarization of the impinging fields through a patch into a substrate integrated waveguide (SIW). The SIWs are loaded with varactor diodes which are biased using coplanar waveguides printed on the back side of the ground plane. There, upon adequate modulation parameters, waves undergo an efficient conversion process towards a desired harmonic and are then radiated back to free space. The photonic Aharonov-Bohm effect is exploited on each cells through modulation signals to independently control the phase and amplitude of the fields radiated with each polarization, thus allowing to obtain any polarization state and achieve nonreciprocity at the polarization level. We envision that this technology will have important implications in wireless terrestrial and satellite communication systems.