A radial line slot array focusing in the near field: Analysis and design

A radial line slot array antenna focusing in its near field is presented. The antenna design is made in such a way to control the side lobe level and beamwidth of the normal component of the electric field with respect to the radiating aperture. A set theoretic approach and alternate projection method is used to derive the aperture field distribution fitting the requirements over the near field. The aperture field distribution is synthesized by properly placing and sizing the slots of the radial line slot array. The antenna is centrally fed by a simple coaxial probe. The antenna design is validated by a prototype and measurements at 12.5 GHz.