Improvement of defocusing techniques for large low-sidelobe phased array antennas

Measurements using a field probe in the radiating near-field region based on defocusing techniques are practical and useful to approximately determine far-field antenna patterns. Especially for measurements of huge scale antennas the defocusing techniques are essential. However, the test distance to focus is generally limited due to both amplitude and phase errors. In this paper, for improving the measurement accuracy of the defocusing techniques, a measurement method modifying excitation element phase of the phased array according to observation points is presented.