A low cost microwave antenna. Microwaves are radiated from or collected by a thin layer radiating-collecting microwave guide section in which a dielectric slab is sandwiched between a metallic bottom plate and a metallic radiating-collecting cover plate. The cover plate contains a large number of slots spaced to produce outgoing or define incoming microwaves beams having directions determined: (1) by the directions of propagation of microwave radiation within the radiating-collecting microwave section and (2) by the frequency of the radiation. In a collection mode, a microwave lens focuses microwave radiation propagating in the waveguide section at focal locations which are dependent on the direction of propagation of the radiation in the waveguide. Alternatively, in a radiation mode, the lens converts microwave energy broadcast from said focal locations into parallel beams propagating in the radiating-collecting microwave guide section.