A novel artificial magnetic conductor (AMC) metasurface is proposed with ultra-wideband 180° phase difference for radar cross section (RCS) reduction.It is composed of two dual-resonant AMC cells,which enable a broadband phase difference of 180°±30° from 7.9 GHz to 19.2 GHz to be achieved.A novel strategy is devised by dividing each rectangular grid in a chessboard configuration into four triangular grids,leading to a further reduction of peak bistatic RCS.Both fullwave simulation and measurement results show that the proposed metasurface presents a good RCS reduction property over an ultra-wideband frequency range.