Coding Engineered Reflector for Wide-Band RCS Reduction Under Wide Angle of Incidence

Abstract

This communication presents the design of 1 bit coding engineered reflector for wideband monostatic/bistatic radar cross section (RCS) reduction under a wide angle of incidence by redirecting the backscattered electromagnetic (EM) energies into wide and countless angles. The proposed surface can achieve an excellent monostatic/bistatic RCS reduction performance of more than 10 dB over a wide frequency range from 60 to 120 GHz under wide angles of incidence up to 75°. This is achieved by designing a wideband anisotropic polarization rotator unit cell with a relative polarization conversion bandwidth of 66.7% and polarization conversion efficiency of more than 99%. The unit cell and its mirrored version are used to represent the “0” and “1” coding states of an optimized 1 bit coding sequence. The distribution of the “0” and “1” coding states and the dimensions of the anisotropic unit cell are optimized carefully, such that the unit cell will have 180° ± 30° reflection phase difference between the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$x$ </tex-math></inline-formula> - and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$y$ </tex-math></inline-formula> -axes over the whole three frequency bands (V-, E-, and W-bands) and obtains ultrawideband and wide-angle diffusion scattering patterns under oblique incidence up to 75°. The simulation and experimental results show that the proposed coding engineered reflector has nearly uniform diffusive scattering characteristics under normal and wide-angle off-normal incidences of EM waves up to 75° over the three frequency bands.