Angular resolution improvement of ocean surface current radar

Abstract

Ocean surface current radar is a Doppler radar to observe oceanographic information using the Bragg scattering resonance mechanism [1]. In this paper, we consider angular resolution enhancement of the ocean surface current radar. The radar employs an antenna array with FM-i-CW operation, then it can resolve angular distribution by Digital Beam Forming (DBF) method and distance can be discriminated by the FM-i-CW radar. In order to obtain sufficient angular resolution, array length should be expanded by increasing the number of elements of the array. Recently, a signal processing technique which can extend the aperture length virtually has proposed, that is called the Khatri-Rao (KR) product array. The angular resolution can be improved without changing the physical aperture length of the array antenna by using this method [2]. The ocean surface current radar is operated in very low frequency. Therefore it is the very important factor to achieve required angular resolution with narrower array length. In this paper, to ensure that the KR product array processing is valid in angular resolution enhancement for the ocean surface current radar, we apply the KR product array to actual data set of the radar and verify the performance.