Planar Lenses for Millimeter Waves

A quasioptical planar lenses based on periodical strip gratings printed on the both sides of a dielectric slab are proposed for millimeter-wave applications. They may be realized using thin-film technology. The lenses based on strip gratings with thin strips (w<<¿) were experimentally and theoretically investigated in two situations: period d is much smaller then wavelength ¿ (closely spaced strip gratings) and d is about ¿/ 2 (array of coupled slot lines (SL)). Eigen waves of the dielectric slab with gratings on its surfaces and diffraction of the dielectric slab surface waves by the lens boundaries were theoretically studied. Electromagnetic field distribution near the focal spot of the lens was experimentally studied. A compact quasioptical multibeam integrated lens antenna was designed, fabricated and tested. By introducing an array of coupled lines with fixed phase shifter to an array of insulated lines good antenna efficiency has been achieved.