SURFACE ERROR MEASUREMENTS OF LARGE REFLECTOR ANTENNAS BY PHASE RETRIEVAL HOLOGRAPHY - AN APPLICATION OF EXTRAPOLATION ALGORITHM

This paper investigates the phase retrieval holography (PRH) method us ing the Misell algorithm for measuring the surface error of a large re flector antenna. PRH is a technique that does not require phase measur ement. The algorithm is investigated experimentally and the estimation errors are evaluated quantitatively using measurement simulation. Fir st, it is shown that estimation errors can be reduced using an initial aperture distribution calculated by ray-tracing. The measurement reso lution is improved by applying an extrapolation algorithm to the Misel l algorithm, Finally, the surface error of a Cassegrain antenna with a n aperture of 64 m to resolution of about 4.1 m in the aperture plane was measured by receiving a test signal from a geostationary satellite (frequency: 1.545 GHz). As a result of the experiment, the surface er ror of 1.57 mm RMS and measurement reproducibility of 0.54 mm RMS were obtained and it was confirmed that this method is effective as a simp le surface measurement method.