Angle and polarization insensitive RCS reduction metasurface based on hybrid mechanism of polarization conversion and absorption

This article introduces the concept, theory, and design of an angle and polarization insensitive radar cross section (RCS) reduction metasurface, using a hybrid mechanism of polarization conversion and absorption. By introducing ladder- and rectangle-shaped metallic patches in the vertical dimension of a 3-D structure, polarization conversion rate (PCR) deterioration, brought by the increase of equivalent substrate thickness at oblique incidences, can be suppressed. Furthermore, lumped resistors are loaded at proper places in each polarization conversion cell, to achieve the power absorption while maintain the angular insensitivity of the PCR. With the above hybrid mechanism, a stable 10-dB RCS reduction can be achieved regardless of the angle of incidence in a wide range and polarization directions. An equivalent circuit model is established for explaining the physical mechanism of the proposed metasurface. For validation, a prototype is fabricated and tested. Measurement results indicate that, for both monostatic RCS at the normal incidence and specular RCS of off-normal incidences from 0° to 45°, a 10-dB TE- and TM-mode RCS reduction can be achieved in the entire X-band (8–12 GHz) and Ku-band (12–18 GHz).