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This paper presents a new method to obtain the deformation distribution onthe main reflector of an antenna only by measuring the electric intensity on aspherical surface with the focal point as the center of the sphere, regardlessof phase. Combining the differential geometry theory with geometric opticsmethod, this paper has derived a deformation-intensity equation to relate thesurface deformation to the intensity distribution of a spherical near-fielddirectly. Based on the Finite difference method (FDM) and Gauss-Seideliteration, deformation has been calculated from intensity simulated by GO andPO method, respectively, with relatively small errors, which prove theeffectiveness of the equation proposed in this paper. By means of this method ,it is possible to measure the deformation only by scanning the electricintensity of a single hemispherical near-field whose area is only about $1/15$of the aperture. And the measurement only needs a plane wave at any frequencyas the incident wave, which means that both the signals from the outer spacesatellite and the far-field artificial beacon could be used as the sources. Thescanning can be realized no matter what attitude and elevation angle theantenna is in because the size and angle of the hemisphere are changeable.

Deformation measurement by single spherical near-field intensity measurement for large reflector antenna