Overview of Novel Post-Processing Techniques to Reduce Uncertainty in Antenna Measurements <s> Noise suppression method <s> Recent planar near-field scanning tests with ultralow-sidelobe antennas have confirmed that random near-field measurement errors will ultimately limit the accuracy of far-field patterns. A formulation is outlined for estimating the spectral signal-to-noise ratio (SNR) arising from noncorrectable near-field random measurement errors. The formulation applies to arbitrarily directive test antennas and probes-even nulling probes. A far-field parameter, called the scan plane coupling factor, may be computed directly from the near-field data, and then used to form the spectral SNR. The accuracy of the spectral SNR is confirmed by simulation and by actual tests with low-sidelobe AWACS array antenna. > <s> BIB001 </s> Overview of Novel Post-Processing Techniques to Reduce Uncertainty in Antenna Measurements <s> Noise suppression method <s> A full characterization of the far-field noise obtained from cylindrical near-field to far-field transformation, for a white Gaussian, space stationary, near-field noise is derived. A possible source for such noise is the receiver additive noise. The noise characterization is done by obtaining the autocorrelation of the far-field noise, which is shown to be easily computed during the transformation process. Even for this simple case, the far-field noise has complex behavior dependent on the measurement probe. Once the statistical properties of the far-field noise are determined, it is possible to compute upper and lower bounds for the antenna radiation pattern for a given probability. These bounds define a strip within the radiation pattern with the desired probability. This may be used as part of a complete near-field error analysis of a particular cylindrical near-field facility. <s> BIB002
Random noise is one of the errors that limit the accuracy of far-field results, particularly, when measuring a low-sidelobe or a high-performance antenna. One possible source for this error is receiver noise that is present in all measurements. Some comprehensive studies for random noise in near-field measurements have already been presented. For the planar system, two independent analyses with similar results have been proposed in (Newell,1988) and BIB001 . A similar study for cylindrical near-field measurements was carried out in BIB002 . These latter publications derived an expression relating the noise power in the near-field a n d f a r -f i e l