A Switchable A-T-A Rasorber With Polarization Selectivity and High Roll-Off Characteristics

Switchable rasorber has attracted a great deal of interest in recent years due to its in-band shielding ability. In this work, a methodology for designing a switchable rasorber with high roll-off and polarization selection characteristics is proposed. The device can be switched between rasorber, polarization selection, and absorber modes, and composed of two resistive layers (a passive and an active resistive layer) and a frequency selective surface (FSS). Transmission zeros are introduced in the FSS design to improve the roll-off characteristic of its transmission band. The PIN diodes on the active resistive layer and FSS can be independently controlled in the orthogonal polarizations to realize the polarization selectivity. The simulation results indicate that the device exhibits a 27.5% fractional transmission bandwidth (3.42–4.51 GHz) under rasorber mode. In addition, the fractional absorption {bandwidth} is as large as 142.9% (1–6 GHz) under absorber mode. A prototype is fabricated and measured to validate the proposed design methodology. This work is promising for designing metamaterials with excellent flexibility and high performance.