Focal spot without the nearest diffraction sidelobes

The authors consider a one-dimensional radiated aperture with a quadratic phase front. The field distribution over the observation plane (a Fresnel area) is analysed. It is required to modify an initially uniform radiated field, so that the diffraction lobes are eliminated over some area of the observation plane. A wave beam from the radiated aperture is focused onto the observation plane. The field distribution represents a general diffraction picture with alternate light and dark bands. The receiving antenna (rectenna) in that plane catches a portion of the microwave radiation and transforms it into direct current.