Switchable Polarization-Insensitive Frequency-selective Surface Reflector/Absorber with Low Profile by Using Magnetic Material

Multi-functional frequency-selective surface reflector (FSSR) is found an applicable candidate for the realization of an antennas RCS reduction in or out of its operating frequency. In this letter, a polarization-selectable in-band switchable FSSR/absorber based on diodes is designed and experimental demonstrated, which comprises a layer of active frequency selective surface (AFSS) and a layer of metal-backed frequency-dispersive magnetic material (FDMM). The design realizes the switching functions of broadband absorption band from 3.5 GHz to 12.0 GHz (110% bandwidth) with at least -10 dB reflectivity and a reflection band at 6.2 GHz with two-sided absorption bands (2.2 GHz to 4.8 GHz, 74.3% bandwidth for the lower absorption band and 7.1 GHz to 12.9 GHz, 58% bandwidth for the upper absorption band) by manipulating the ON and OFF states of PIN diodes. Besides, due to the use of FDMM, the thickness of the FSSR is only 0.074L, making it easy to design the reflective surface of the antenna. The physical mechanism of this work is demonstrated from the circuit point of view by an equivalent circuit model. A prototype of the proposed FSSR/absorber is fabricated and measured, where reasonable agreement is observed.