Minkowski inspired circular fractal metamaterial microwave absorber for multiband applications

A Minkowski-inspired circular fractal microwave absorber has been presented, operable at multibands between 1 to 18 GHz. The proposed absorbing structure is constituted with novel geometry of second-order circular fractal rings impinged on a dielectric substrate backed by a metallic layer. The ability of miniaturization offered by a unique Minkowski circular fractal geometry has been exploited for the unit cell designing of a multiband absorber with a smaller dimension. The nearly perfect absorption of multiple peaks is persistent with polarization variation, and the impact of variation in the angle of incidence under transverse electric (TE) and transverse magnetic (TM) modes was also elucidated. The electric-field distribution and surface-current density at the resonating frequencies have been studied to better understand the absorption mechanism. The designed absorbing structure has been fabricated and a free-space microwave measurement setup has been used to measure it. The good miniaturization capabilities, strong absorption at multibands, insensitivity to polarization angle variation, and good angular stability qualify the proposed absorber for scientific and military applications.