Broadband array antennas using a self-complementary antenna array and dielectric slabs

It is well known that planar self-complementary structures have a constant input impedance and hence they are good candidates for ultra-wideband antennas. However, introduction of a ground plane breaks the symmetry and destroys the broadband property. In this paper, it is shown that stacking of dielectric slabs above the antenna elements can reduce the degrading eject of the ground plane. The dielectric slabs act as filters adding loops in the center of the Smith chart. The results are illustrated with infinite antenna arrays with broadside bandwidths of 4.7:1 at -13dB and of 5.5:1 at -17dB for the cases of two and three dielectric slabs, respectively.