Unit Cell for Reflectarrays Operating With Independent Dual Circular Polarizations

International audienceA unit cell for dual-circularly-polarized (CP) re-flectarrays illuminated by a dual-CP primary feed is designedand validated experimentally around 8.5 GHz. It is composed oftwo layers reflecting independently and simultaneously the twoincident circular polarizations. The first layer is a circular polarizationselective surface (CPSS) based on an enhanced version ofthe original Pierrot’s cell with multiple wires bent in a crank-likeshape. The second layer is made of dipoles printed on a groundedsubstrate; it is used to reflect the incident right-hand CP (RHCP)wave transmitted through the CPSS with a 2-bit phase resolution.This letter demonstrates that the sole association of both layersis not sufficient to reach the expected behavior. An additionaloptimization step is required to cancel out uncontrolled reflectionsand improve isolation between both polarizations. The simulatedand measured characteristics are in good agreement for the twocircular polarization