Harmonic-Absorption Frequency Selective Rasorber Based on Non-Resonant FSS and Resistive-Sheet

In this article, we proposed a harmonic-absorbed frequency selective rasorber (HA-FSR). It consists of a non-resonant frequency selective surface (FSS) with inductive square loops, capacitive patches, and resistive sheet-based absorbers. The non-resonant FSS is of harmonic-suppression (HS) feature, which is free of spurious harmonic transmission bands up to three octaves of the main passband. We introduced resistive sheets on both sides of the HS-FSS to perform wideband absorption. Full-wave simulated and measured results both show that the proposed HA-FSR owns main passband with -3-dB bandwidth of 3 GHz at the X-band and -10-dB absorption band from 20 to 30 GHz. The frequency range of harmonic-absorption covers from around two to three octaves of the passband. The proposed HA-FSR can be applied in electromagnetic (EM) shielding and low-observable platforms.