Metamaterial-based 3-D Frequency-selective Rasorber

A novel metamaterial-based 3-D frequency-selective rasorber (FSR) with wide low-insertion-loss passband and two-sided absorption bands is proposed. Two types of symmetric lossy split-ring resonators are employed in the unit cell of the periodic structure to produce the lower and upper absorption bands, respectively. It is shown through simulation that a low-insertion-loss (vertical bar S-21 vertical bar >=-1dB) passband can be obtained from 5.7 to 8GHz with the minimal insertion loss of 0.6dB around 6.5GHz and the fractional bandwidth for at least 10dB reflection reduction within the lower and upper frequency bands is 110% under normal incidence. Furthermore, by properly covering a pure PEC-backed dipole antenna by the proposed 3-D FSR array, a low-RCS antenna system is constructed, which exhibits a remarkable out-of-band radar cross section reduction (RCSR) and the enhanced radiation characteristics. It is expected that the proposed 3-D FSR design may be favorable for stealthy radome technologies.