Near-field measurements on plane-polar facility

The authors describe far-field predictions obtained on a plane-polar facility. The procedure for the transformation of the near-field to the far-field uses a fast algorithm for the calculation of the radiation integral and is presented in the form of a cross correlation which is carried out using the fast Fourier transform. Predictions of the far-field patterns of two antennas are shown. A numerical algorithm for the interpolation of the near-field from the plane-polar grid to the cartesian grid is derived and the interpolated data is used to predict the far-field patterns of the two antennas. A direct result of the interpolation to a cartesian grid is the adaptability of the near-field to processing for antenna metrology, enabling the surface diagnosis of antennas under test from measured plane-polar data. A technique for phase drift compensation is presented and verified. The phase drift compensation procedure is particularly suited for the plane-polar geometry.