The determination of the aperture distribution of a linear array through near field measurements

An experimental approach for finding aperture distributions of linear array antennas is described and applied to a particular antenna. The approach utilizes a discrete source synthesis technique in which measurements of the radiated near field are substituted for the so called desired field, and element currents are calculated. Four sets of near field measurements were taken and are presented along with various current solutions. Checks on solution accuracy were accomplished through comparing computed near and Fresnel fields with measurements. It was found that fields computed from these currents correlated well with the radiated fields of the antenna. Solution reactivity was checked through inspection of the invisible regions of computed far field radiation plots of the currents isolated in free space. Both measurement sampling distance and measurement range were varied in an effort to assess limitations of the technique.