Reconfigurable Multiband Rasorber With Identical Metallic-Strip-Based Configuration Layers for Coordinated Absorbing/Transmitting Design

In this letter, a novel technique for constructing multiple passbands in an active absorber is proposed. Unlike conventional fragmented designs, the lossless reflective layer is produced by eliminating loss from the lossy layer, leading to the additional benefit of a more adaptable multiband match. The series-embedded resonator integrated with p-i-n diodes is presented to switch the open-circuit frequencies, allowing multiple windows to switch between transmission and absorption modes over a flexible frequency range. Consistent metallic-strip-based configuration ensures consistent transmission characteristics for both layers under the same control scheme, facilitating coordinated design for transmission/absorption in multiple bands. A prototype of the active rasorber is fabricated for demonstration. The single-polarized response of the structure has been validated in the polarization direction parallel to the metallic strips. The transparent windows can be toggled between dual-pass-band mode (A-T-A-T-A) at 3.5 and 8 GHz, and single-pass-band (A-T-A) mode at 6 GHz. Flexible frequency ratios of 2.3:1 and 1.33:1 are achieved. The reflection is effectively suppressed when the window is closed, and it consistently exhibits such behavior outside the window. The operation principles and design procedure are presented.