Low angular-dispersion microwave absorption of a metal dual-period nondiffracting hexagonal grating

Abstract

The microwave (11.3<λ0<16.7 mm) reflectivity response of a nondiffracting dual-period hexagonal grating is explored. In three directions at 60° to each other, the aluminum grating has a repeat period of 7.2 mm in which are three equally spaced grooves, one being slightly shallower than the other two. This dual-period (λg and λg/3) structure exhibits strong microwave absorption at several different frequencies. In addition, some of the absorptions are almost completely independent of the angle of incidence and polarization of the microwave radiation.