DOA estimation without antenna characteristics calibration for UWB signal by using sub-band processing

High resolution method for direction of arrival (DOA) estimation using array antenna is studied actively. In almost previous studies, it is assumed that the antenna elements have the same directional patterns. However, it is very difficult to make many antenna elements they have just the same directional patterns. Furthermore, the directional patterns are distorted due to mutual coupling between the antenna elements. The estimation accuracy is decayed if the directional patterns are distorted intensively. Generally, to avoid the effect of directional pattern distortion, antenna characteristics are calibrated before the estimation, however, it is difficult to cancel the effect of distortion when the arrival signal is very wideband because the directional patters depend on the frequency. In this paper, sub-band technique to decrease the effect of antenna pattern distortion is proposed. In the proposed scheme, received wideband signal is divided into several frequency bands and DOA is estimated in the respective frequency bands. By averaging the estimated results, the effect of antenna pattern distortion will be reduced. In the following section, configuration of proposed system is explained first. After that the effect of number of sub-band and effect of antenna characteristics on DOA estimation accuracy is discussed.