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Checkerboard AMC Surface for Ultra-wideband Radar Cross Section Reduction

In this paper, an ultra-wideband metasurface based on optimized multielement phase cancellation (OMEPC) is proposed for radar cross section (RCS) reduction. The square ring structure with adjustable size is chosen as the basic unit cells. Metasurfaces based on the traditional method of opposite phase cancellation (OPC) is designed by combining two unit cells with an approximately 180° phase difference, which has a narrow bandwidth for phase cancellation. The bandwidth and oblique incidence performance of RCS reduction are two critical factors of stealth technology. More unit cells enable the phase difference between them to be relatively stable when the frequency is changed, which extends the bandwidth of RCS reduction. Based on the array pattern synthesis theory, the PSO algorithm is used to make the search of the optimal unit cells. The designed 16-element artificial magnetic conductor (AMC) surface can realize a 10 dB RCS reduction in a superwide frequency band ranging from 5.67 to 18.72 GHz with a ratio bandwidth (fH/fL) of 3.3 : 1 under normal incidence for both polarizations. Compared to the previous researches for planar checkboard metasurface, the proposed metasurface has a wider bandwidth. Furthermore, the performance of the proposed metasurface were studied under the oblique incidence with incident angle of θ = 20° and θ = 30° for both transverse-electric (TE) and transverse-magnetic (TM) polarizations. Significant RCS reduction is also achieved under oblique incidence, which shows the excellent performance of destructive interference. The theoretical analysis and simulation results are in good agreement and demonstrate the proposed metasurface can realize an ultra-wideband RCS reduction.