A dual-operating-band planar horn antenna having very low profile is presented in this paper. By opening a subwavelength aperture into a corrugated conducting plate, good return losses and a narrow radiated beam in each of the two desired operating frequency bands can be measured. This behavior is very similar to that observed in optical wavelengths where enhanced transmission was measured through apertures etched in metallic corrugated plates. Here, the double-corrugated structure has been scaled into the microwave frequency range and the excitation has been done by a conventional closed metallic waveguide placed in the rear part of the structure. In this way, a new concept of a very low profile feeder is proposed with potential wireless applications.