Abstract
Linear, planar and cylindrical antennas of diffraction radiation have obtained wide distribution over the recent years. With large apertures they provide formation of narrow wave beams. However, antennas capable of strongly focusing electromagnetic waves quite often prove to be in demand as well. Traditionally, the problem of focusing is solved through the use of lenses. However, in some situations, especially, in radiometry, occurrence of a dielectric lens in an antenna of millimeter and all the more of submillimeter wavelength range can adversely affect performance of the whole system. In the paper, a new kind of diffraction antenna is suggested, which involves a focusing reflection grating. Focusing properties of cylindrical reflection gratings of circular and parabolic profiles are considered.