A Method for Designing Multi-Band Rasorbers for Wideband Applications

Rasorbers with a single passband (narrow or wide) or multiple narrow passbands have been reported for stealth applications over the past few years. In this work, a method of designing the multi-band rasorber with wide passband(s) is proposed for the stealth of wideband antennas. Firstly, the method of designing multi-band FSS is proposed based on the theory of N-band resonator, in which all the passbands exhibit second-order response. Secondly, a parallel resonator combining spiral inductor and interdigital capacitor is proposed to satisfy wide passband requirements at lower frequency of the operating band. Finally, to verify the proposed method, a dual-band rasorber consisting of FSS and resistive layer is fabricated and measured. The measured results illustrate two passbands within 4.9-6 GHz (20.0%) and 8.6-9 GHz (6.3%), respectively. Three absorption bands with 48.4%, 25.7%, and 22.0% fractional bandwidths are also achieved.