Ultrathin and Simple Frequency Selective Rasorber Based on Ferrite Absorber with Embedded Epsilon-Near-Zero Tunneling Channels

An ultrathin and simple frequency-selective rasorber (FSR) with a passband located within a wide absorption band is proposed. The ultrawide absorption band is obtained by employing commercial magnetic materials in the absorption channel and the passband is realized using epsilon-near-zero (ENZ) tunneling waveguides. The attractively ultrathin and simple feature is achieved by utilizing tunneling effect at the cutoff frequency of metallic waveguides with arbitrary length, permitting the overall thickness shrink into to the same as that of the absorber.