Calibrated_Time-Frequency_MUSIC method for direction of arrival measurement of pilot signals

The accuracy of the microwave (MW) power beam steering is one of the most critical goals for Solar Power Satellite (SPS). Retrodirective beam control system is the proposed method of beam steering technique for SPS. Detection of precise Direction of Arrival (DOA) of the pilot signal in SPS system is an integral part of the retro directive beam steering. High precision DOA estimation methods like MUltiple SIgnal Classification (MUSIC) and Time-Frequency_MUSIC (TF_MUSIC) based methods require calibration of antenna gain and phase errors prior to the DOA estimation. TF_MUSIC method of DOA detection can increase the effective SNR but its performance also degrades if antenna gain and phase errors exist. The performance of conventional MUSIC was tested by an experiment. Antenna gain and phase errors were calibrated by using the MUSIC method and at the same time the DOA was estimated by calibrating the gain and phase errors and the method is named as Calibrated_MUSIC (C_MUSIC). C_MUSIC performed better than MUSIC. The performance of TF_MUSIC was also tested by the same antenna calibration data and it was found that this Calibrated_TF_MUSIC (CTF_MUSIC) performed better than the MUSIC and C_MUSIC.