Abstract：High frequency ground wave(HFGW) radar antenna arrays always have amplitude-phase errors; thus, when the antenna pattern is changed, the clutter cancellation algorithm must be recalibrated. The existing calibration methods include using an auxiliary source, building an array model for parameter estimation, and using the noise or clutter as a calibration source. However, the first method is expensive, the second has poor real-time performance, and the third cannot calibrate the phase error. This paper presents a hierarchical calibration algorithm using isolated large targets. The array is divided into several subarrays with a high SNR target which is unique in the spatial and Doppler domains as the calibration source. Then, the errors in each subarray are calibrated using the improved noise subspace fitting method or the phase difference calibration method to get a uniform error vector by integrated each subarray error vector to calibrate the entire array's amplitude and phase errors. The calibration significantly reduces the amplitude error, phase error and the sidelobe of the antenna pattern. Both theoretical results and tests show that this calibration method greatly improves the accuracy and real-time response than the traditional algorithm.
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