Near-Field Calibration for Large Reflectors

摘要

This paper presents a 'mid-range' calibration technique, now being developed for a 60 ft. diameter reflector site. With this technique, near-field amplitude and phase is collected at a calibration tower as the reflector scans across it. The mid-range 'near-field' data is then transformed to a far-field pattern using a Fourier transform technique. Information on far-field EIRP, directivity, pointing, axial ratio and tilt, as well as encoder timing is obtained with accuracies comparable to standard measurement techniques. A particular advantage is that the system, once set-up, can be used on a regular basis without impacting site operations.