Ultrawideband Radar Cross-Section Reduction by a Metasurface Based on Defect Lattices and Multiwave Destructive Interference

A metasurface based on defect lattices and an alternative physical mechanism, multiwave destructive interference (MWDI), is proposed for ultrawideband radar cross-section (RCS) reduction. The bandwidth of RCS reduction (sigma(R)) is greatly expanded by second destructive interference. The metasurface is composed of 16 basic defect lattices. First, the defect lattice can generate primary destructive interference with the capacity of RCS reduction and amplitude-phase manipulation, which consists of an aperiodic array of square rings with an embedded cross. Second, the interference between multiple backscattered waves produced by the defect lattices at multiple frequencies sampled in an ultrawide band is simultaneously manipulated and optimized by the principle of superposition of waves and particle swarm optimization (PSO) to obtain second destructive interference. The metasurface enables a 10-dB RCS reduction over an ultrawide frequency band ranging from 6.16 to 41.63 GHz with a ratio bandwidth (f(H)/f(L)) of 6.76:1 under normal incidence for both polarizations. The estimated, simulated, and measured results are in good agreement and prove that the proposed metasurface is of great significance for bandwidth expansion of RCS reduction.