From near–field measurements to the antenna directivity

A procedure for evaluating the antenna directivity from near-field measurements on a spherical scanning surface is proposed. It uses a closed form formula for computing the total radiated power from the knowledge of the radiation intensity samples on the far-field sphere. These last, which are even in number on each parallel, are determined via an efficient probe compensated near-field - far-field transformation technique based on a nonredundant sampling representation of the probe voltage. This allows one to reduce significantly the number of required data. The effectiveness of the proposed procedure is assessed by numerical simulations