Backward RCS reduction by gradient index meta-surface composed of polarization independent ring-shaped patches

A polarization independent ring-shaped gradient index meta-surface for radar cross section (RCS) reduction is proposed. The design can provide a discontinuous gradient phase distribution of reflected wave, which can transform the incident wave to surface wave bounded on the meta-surface. The ring-shaped patches are attached to a high dielectric constant substrate with a perfect electrical conducting (PEC) ground. Dimensions of the ring-shaped unit cells are adjusted to get the desired gradient phase distribution. Simulation results show that the backward RCS can be reduced as large as 10 dB comparing with the same size metal plate, and this reduction is independent on the polarization of incident wave.