Phased Array Antenna Calibration with Probe Positioning Errors [Measurements Corner]

Calibration is often performed inservice with a calibration probe (CP) located in the far field (FF) of the antenna under test (AUT). Nevertheless, in some cases, it is suitable to work in the near-field (NF) environment. NF calibration is especially useful for large-aperture phased-array antennas (PAAs), when it is often complicated to arrange the CP in the FF of the antenna array. Recalculating complex initial coefficients from the NF to the FF requires taking into account distances between the phase centers of the emitters of the channels under test and the phase center of the CP. In this article, the influence of errors in the determination of coordinates of a CP on the calibration results, together with antenna pattern distortions, are considered. The derived formulas could be used to produce new requirements on the accuracy of an AUT in a CP survey.