Measurement of the Rotation Center From the Received Signals for Ultrahigh-Resolution Radar Imaging

In this letter, we propose a method for estimating the center of rotation on an experimental radar imaging. The experiment is performed with tomographic approach to obtain the radar cross section images of the target on a rotation table. In an ultrahigh-resolution imaging using tomographic reconstruction, precise knowledge of rotation center of the turntable position is necessary since this has a big influence on the image quality. The position of rotation center can be physically measured, but the result is not accurate due to the delay introduced by the RF components and cables. Thus, we present a method to precisely determine the rotation center based on the rotational symmetry of the received data. The proposed method is verified by doing imaging of several targets using ultrawideband radar with picosecond-length pulses. The system bandwidth is larger than 30 GHz, and the imaging results have subcentimeter resolution.