Synthesis of parabolic reflector antenna patterns using optimized array feed

The authors discuss the results of their study on properly excited array feed that yields the required pattern for rotationally symmetric parabolic reflectors with planar array feed. The radiation field of the array feed reflector antenna can be written as the superposition of the radiation due to the individual elements. The far field radiation pattern of each individual array element is calculated by direct evaluation of the physical optics radiation integral. They present a derivation of physical optics radiation integral for an arbitrary offset feed rotationally symmetric parabolic reflectors. The excitation conditions (phase and amplitude) of the array elements are calculated using the least squares minimization method. Both co-polar and cross-polar radiation patterns are optimized when the elements of array feed are Huygens sources. The study shows that substantial side lobe reduction for bore sight direction is achieved by adjusting only the excitation coefficient for the rotationally symmetric parabolic reflector. It has also been observed that the beam can be tilted and scanned by using this method