Investigations into electronically controlled rings with arc stubs phasing elements for reconfigurable microstrip reflectarrays

The paper presents new electronically controlled phasing elements for a beam steered single-layer microstrip reflectarray operating at 4.0GHz. The phasing elements are formed by printed circular rings equipped with variable length arc stubs. Two phasing methods are considered, one when all elements are individually controlled, and two, when gathered elements are controlled. In the gathered configuration, two adjacent elements are used to obtain two different phase compensation values. The two phasing methods are demonstrated in the design examples of reflectarrays having their main beams steered between 20° and 30° from the broadside direction. Full wave simulations with CST Microwave Studio are performed to investigate the resulting radiation patterns. The obtained results show that the two phasing methods produce similar radiation patterns around the desired directions. However, the reflectarray using gathered elements suffers from an increased level of grating lobe.