Calibration and Evaluation of a Circular Antenna Array for HF Radar Based on AIS Information

High-frequency (HF) ground-wave radars employing compact antenna arrays are advantageous in practical applications because of their convenient deployment. However, the direction-of-arrival (DOA) estimation accuracy may significantly degrade in the presence of array errors for compact phased-array HF radars. Consequently, wind, wave, and current measurements would become unavailable for further applications. In this letter, an array calibration method is proposed for an HF radar system based on a circular antenna array. First, an array manifold model containing array errors is established. Second, a calibrated array manifold is obtained by fitting and interpolating the responses of ship echoes using a least squares fitting method. Finally, the calibrated array manifold and the noise subspace matrix are substituted into the multiple signal classification (MUSIC) method to estimate the DOA of each ship echo. The results indicate that this calibration method significantly reduces the DOA estimation errors with the root-mean-square errors of less than 10°.