Optimizing Mutual Coupling Measurements for Active Phased Array Radar Calibration

This paper presents experimental results of a radar calibration for an all-digital phased array using mutual coupling (MC) measurements. Three signal processing techniques are applied to the measurements to improve the Signal-to-Noise Ratio (SNR) of distant couplings. A calibration procedure based on the far-field radiation patterns of truncated near-field measurements is used to quantify the effectiveness of the calibration. Root Mean Square Errors (RMSE) for magnitude and phase are estimated between the weights derived from radiation patterns and those from MC measurements. Results show improved SNR in the couplings as well as higher accuracy in the derived calibration weights when match filtering techniques are used in the MC measurements.