A new concept of focusing antennas using plane-parallel Fabry-Perot cavities with nonuniform mirrors

An original configuration of low-profile directive antennas is presented in V-band. The focusing effect is performed by a plane-parallel Fabry-Perot (FP) resonator illuminated by a printed antenna. Both reflecting mirrors are made of metal strip gratings. The dimensions of the strips and slots of the nonperiodic output mirror are much smaller than the working wavelength; they are computed locally so that this mirror behaves as a spherical equiphase surface. Theoretical and experimental results show that the radiation patterns are symmetric and have low sidelobes. The antenna directivity is controlled by the value of the synthesized radius of curvature, that is to say by the nonperiodic distribution of the metal strips. It typically varies between 15 and 23.5 dB at 60 GHz. This new radiating structure is much more compact than substrate lenses and is compatible with low-cost multilayer technologies at millimeter wave frequencies. This is a possible candidate for user mobile-stations of indoor broadband communication systems.