ON-BOARD PHASE AND MODULUS CALIBRATION OF LARGE-APERTURE SYNTHESIS RADIOMETERS - STUDY APPLIED TO MIRAS

On-board calibration of bidimensional aperture synthesis radiometers w ith a large number of antennas by the standard correlated noise inject ion method is technologically very critical because of the stringent r equirements on mass, volume, and phase equalization of the noise distr ibution network. A novel approach, which makes use of a set of uncorre lated noise sources uniformly distributed in the array, is proposed in this paper. Each noise source drives correlated noise only to a small set of adjacent antennas. These sets of antennas are overlapped in or der to maintain phase and modulus track along the array, This approach reduces drastically mass and volume of the noise distribution network , Moreover, its phase matching requirement is strongly relaxed because it is only necessary within small sets of adjacent antennas. Power st ability of the uncorrelated noise sources is also not a stringent requ irement, This procedure allows independent phase and modulus calibrati on by making use of a reduced number of redundant correlations.