Elimination of Scan Blindness in Phased Array Antennas Using a Grounded-Dielectric EBG Material

In printed phased arrays, scan blindness occurs when the propagation constant of a Floquet mode coincides with that of a mode supported by the homogeneous substrate, resulting in large input mismatch and in a propagating mode with complex propagation constant. In our study we analyze the possibility to replace a standard homogeneous dielectric substrate with a grounded dielectric EBG substrate to eliminate scan blindness. We present here the main idea for the design, the dispersion diagrams of a dielectric EBG material with metallic patches to show that there are no surface modes (waves guided by the structure with real propagation constant), and the active reflection coefficient and input impedance for various frequencies. Furthermore, at a chosen operating frequency the active reflection coefficient for the phased case indicates that there is no scan blindness effect.