Broadband Reflective Frequency Selective Surface Unit-Cell at X- and Ku-band

The broadband frequency selective surface (FSS) unit-cell in left-handed circular polarization (LHCP) is introduced in this paper. The unit-cell operates across the X- and Ku-band as a bandpass filter. The sub-wavelength periodicity is around 5-mm. The -1-dB bandwidth spans from 8.18 GHz to 17.25 GHz for 75.6% at 12 GHz. At various oblique incidences, the FSS unit-cell maintains its operation with quasilinear phase response within the bandwidth. The success of the unit-cell operation motivates the experimental characterization of a complete FSS.