Ultra-wide-band microwave composite absorbers based on phase gradient metasurfaces

In this paper, we propose to realize ultra-wide-band absorber (UWBA) based on anomalous refraction/reflection of phase gradient metasurfaces (PGM). To achieve high absorption and meanwhile keep small thickness at low frequencies, PGM is incorporated into conventional magnetic materials (MM). The absorptivity is increased due to prolonged propagation length in the MM, which is produced via anomalous refraction/reflection mediated by the PGM. Three typical composite configurations of PGM-based absorbers are investigated and an UWBA design method is finally formulated. Due to small thickness and ultra-wide bandwidth, such absorbers possess great application potentials in EM protection, RCS reduction, etc..