Extending the capabilities of the GRASP and CAESAR software to analyze and optimize active beamforming array feeds for reflector systems

This paper describes a numerical approach for the analysis of a reflector antenna system which is fed by a Phased Array Feed. This approach takes mutual interaction effects into account between the antenna array and the low noise amplifiers in the evaluation of the system sensitivity and optimization of the beamformer weights, and can be used when several signal and noise sources are present on the sky, ground, and inside the system itself. The described methodology has been applied to a practical PAF (comprising 144 tapered slot antennas operating from 1 to 1.75 GHz) which is installed at a 25-m reflector antenna. Comparison of numerical and experimental results shows a good agreement.