Three dimensional dual-band phase gradient metamaterial based on Pancharatnam-Berry phase

A three dimensional (3D) dual-band phase gradient metamaterial (PGM) is proposed based on the Pancharatnam-Berry phase approach in this work. First, a 3D dual-band co-polarization reflection metamaterial under circularly polarized (CP) wave incidence was achieved by a vertical metallic Split-Ring Resonator (SRR). The co-polarization reflection efficiency is more than 90% over the spectra 4.78 GHz–4.92 GHz and 11.2 GHz–12.8 GHz. The underlying physical mechanism for co-polarization reflection is analyzed by using the scattering matrix approach. Then, the dual-band PGM is constructed by utilizing the vertical metallic SRR with different rotation angles. The PGM can achieve surface wave coupling and efficiently anomalous reflection, respectively, in the two spectra under CP wave incidence. Due to the opposite phase gradients for left-handed circularly polarized and right-handed circularly polarized wave incidence, the incidence linearly polarized wave was divided into two beams of CP waves and coupled into surface waves or anomalously reflected along opposite directions. Both the simulated and measured results demonstrated the great performances of dual-band PGMs.