Array Calibration using Measured Data for Precise Angle-of-Arrival Estimation
Panarat Cherntanomwong, Jun‐ichi Takada, Hiroyuki Tsuji, Ryu Miura · 2005
In this paper, array calibration methods using the real measured data have been investigated. A set of measured data is collected from a single source whose angle of arrival (AOA) is varied. Several calibration techniques are presented. The first one is a simple calibration method to compensate amplitude and phase errors between array elements. However, from the AOA estimation result, it is found that the calibration data based on the amplitude and phase compensation are effective only to estimate AOA close to the angle of the signal used to calculate the calibration data. We found that the phase differences of calibration data change with AOA while the amplitude differences do not change with AOA. Therefore, for the second calibration technique, we propose the least square fitting to approximate the phase differences to a polynomial function of AOA and then modify the calibration data. The result illustrates the improvement of the calibration data when the least square function is applied to the phase differences. Moreover, the third calibration technique based on a signal subspace approach is proposed. From the result, it is shown that this technique is also effective in some extent and tends to improve the performance if the number of the received signal increases. To demonstrate the effectiveness of the calibration method, AOA is estimated by the MUSIC algorithm. Keywords—Antenna array, Array calibration, AOA estimation