Low Reflection of Antenna with Wideband Reduced Backscattered Field Based on Phase Interference Technique

Abstract

The approach of an asymmetrically designed checkerboard as a reflecting metasurface and the coding diffusive surface is proposed as a new way to minimize the antenna backscattered electromagnetic field level. At the resonant frequencies of three different metasurface units, zero degrees reflection phase is achieved. An active phase difference of 180° is maintained between three artificial magnetic conductors (AMCs) unit cells over a wide bandwidth of frequencies so that backscattered electromagnetic wave energy can be directed at different oblique angles using phase interference to reduce radar cross section. Comparatively, three AMC cells are arranged as an asymmetric chessboard along with an arbitrary phase distributed reflecting screen constructed using the random phase distribution technique. Further, compared with the reference antenna, the asymmetric chessboard has a greater reduction in backscattering. The proposed methodology is based on the backscattered field-level cancellation and diffusion. The simulations demonstrate remarkable backscattered energy reduction from 4.9 to 18 GHz for the proposed antenna operating at 11 GHz in normal polarization (x- and y-polarization). In addition, −10 dB backscattering reduction is achieved in the antenna working band (10.3–11.9 GHz), and different AMC units working at different frequencies exhibit the same radiation properties. Further, in/out-of-band bistatic reflected electromagnetic energy levels are significantly reduced. Similarly, the full-wave simulation of the fabricated prototype confirms the measurement results.