Analysis of Two-Probe Position Estimation Technique for On-Site Calibration of Large Digital Arrays

To ensure stable operation of the large active phased-array used in space surveillance radars, periodic in situ calibration is required. Because the positional accuracy of the probes employed for calibration directly affects calibration performance, an accurate probe localization procedure is necessary. When the two probes are used, their positions can be estimated without auxiliary external alignment equipment. To examine the validity of this approach, we analyze a theoretical model and summarize the localization results obtained from simulations under symmetric configurations. The analytical results indicate that the estimation performance improves as the probes are placed closer to the measurement array, and as the inter-probe angular separation increases, suppression of correlated noise is required for stable estimation. The simulation results further demonstrate that when the probe spacing is maintained at a level comparable to the aperture length of the measurement array and the correlated noise is low, the probe positions can be estimated with an error on the order of 0.02 λ.