ITERATIVE PHASE CALIBRATION PROCEDURE FOR PLANAR PHASED-ARRAY ANTENNAS

The far-field pattern of an aperture antenna can be utilized to reconstruct the aperture electric field distribution in terms of amplitude and phase by means of a method based upon the plane-wave spectrum (PWS) formulation using the Fourier analysis. As an alternative to the direct current measurement technique this method can be used to identify any significant defective elements at an array antenna. A specially interesting application is the phase calibration of low sidelobe phased arrays. A very precise, self-contained phase calibration procedure is presented which as input data needs the samples of the scanning array far-field pattern. For those patterns measured in the Fresnel region the antenna is focused within the Fresnel region by introducing a phase correction term into the electric current distribution. Tests at a developed S-band phased array show that by the proposed procedure a phase accuracy have been achieved within the phase accuracy of the installed phase shifters (+/- 3-degrees).