Broadband Frequency-Selective Rasorber With Varactor-Tunable Interabsorption Band Transmission Window

Reconfigurable Frequency Selective Rasorber Covering Extremely Wide Transmission Frequency Range

“…While the other reconfigurable rasorbers exhibit a single passband under all conditions, the proposed rasorber can be switched between modes with single, dual and triple transmission bands with at least one absorption band. Hence, the proposed device greatly outperforms the other counterparts in terms of the overall fractional transmission frequency range (63.9% vs. 26.7% in [30]), demonstrating excellent frequency reconfigurability of the proposed rasorber while maintaining a wide absorption bandwidth.…”

“…As well known, the capacitance of varactor diode can be tuned by varying the reverse bias voltage applied between its anode and cathode. In [30] and [31], the varactor diodes are connected in parallel with the geometrical capacitance, as shown in Fig. 8(a), resulting in a tunable capacitance to control the resonance frequency.…”

“…In addition, reconfigurable rasorbers are also suitable to be used as the radome materials for the radar cross section (RCS) reduction of reconfigurable antennas within its absorption band. In early 2019, L. Wu et al reported a tunable A-T-A rasorber with fast roll-off characteristics on both sides of the passband [30]. However, the minimum insertion loss as high as 3.3 dB makes it unacceptable for practical applications.…”

Dual-Band Diffusive Metasurface-Based Reflector With Low Out-of-Band Backscattering

“…, (6) where and are the elevation and azimuth angles of an arbitrary direction, respectively; (m, n) defines the position of the element; and (0 or ) represents its scattering phase. To manipulate the scattering pattern as much as possible, the peak value of the scattering field can be expressed as the fitness function fitness = max(SP( , )).…”

“…The element distributions of a chessboard metasurface and a diffusive metasurface are calculated by MATLAB through (6) and 7, as shown in Fig. 8(a) and Fig.…”