Switchable Polarization Insensitivity Radar Absorber/Reflector Based on Active Frequency Selective Surface

In this article, a switchable polarization-insensitive lower thickness active frequency selective surfaces (AFSSs) absorber/reflector is proposed. The proposed structure consists of the top AFSS layer, which contains four patches and four pairs of PIN diodes in parallel with resistors, the upper substrate I, a metal ground, the bottom substrate II, and a simple bias network behind the bottom substrates that effectively reduce unnecessary disturb. The PIN diodes are controlled by the bias networks through the metalized via holes to obtain the switchable properties. The polarization-insensitive performance is realized by symmetrical structure. The resistors in parallel with PIN diodes load between every two patches to enlarge the resonant bandwidth. One remarkable feature of the structure exists in it can be switched in a variety of operating states to control the visibility of the target in radar systems. When it operates as an absorber, it has a stable absorptivity, which is more than 85% in the frequency range of 12.6–25 GHz with a small radar cross section. The equivalent circuit model, surface loss density, and surface circuit distribution are provided to assist in understanding the physical property of the entire design. A configuration of the structure is fabricated and the measurement results demonstrate a reasonable agreement with the simulate ones, thus confirming the proposed concept.