Multifunctional Electronically Reconfigurable Electromagnetic Surfaces for Ka-Band Antennas

This paper presents the design and performance of two novel Ka-band reconfigurable unit-cells, using p-i-n diodes, for electronically controlled intelligent surfaces. The first cell operates in reflection or in transmission mode, by properly biasing its 4 diodes, and achieves a 1-bit and 2-bit phase quantization, respectively. The second cell comprises the first one, in transmitting mode, and a reconfigurable linear-to-circular polarization converter with 2 diodes, spaced by an air gap. It radiates a circularly-polarized wave with switchable handedness. The possibility of realizing wide-angle scanning and polarizationagile transmitarray antennas attaining limited phase quantization losses and enhanced aperture efficiency with respect to the state of the art is experimentally and numerically demonstrated.