Phase correction of an HF multireceiver antenna array using a radar transponder

We present the method we used to calibrate the multireceiver antenna array of the HF backscatter radar located at Valensole (43/spl deg/48'N, 6/spl deg/06'E) in south France. During the first experiment with the new receiving equipment the internal phase calibration procedure, using an injected signal, did not work correctly because of hardware problems in the antenna system, so we decided to use the signal of an available radar transponder to measure the errors in the phases and to compensate for them. This was done by computing a DFT on the signal of each receiver output and by averaging to estimate a correction vector to be applied to the data before performing the classical beamforming. We present data showing that this method gives good results. We also compare with the results we obtained in a second experiment when the internal phase calibration procedure worked correctly.<<ETX>>