Focusing Metasurface with Frequency Select Surface

In this paper, a band-pass transmission phaseshifting metasurface unit cell is designed by combining frequency selective surface and Huygens surface. The antenna gain can be improved by arranging the band-pass transmission phase-shafting metasurface unit according to the focusing formula. This paper only introduces the double-layer cascade band-pass transmission phase-shifting metasurface unit cell. In the upcoming work plan, a checkerboard metasurface or an absorbing metasurface will be designed to achieve out-of-band stealth functionality. The metasurface works at $8 \sim 12 \mathrm{GHz}$, and the insertion loss of the metasurface is less than 3 dB in the passband, the metasurface has 315° phase shift.