Multipath angle estimation for low-flying target of multi-frequency shipborne radar

Abstract

If two signals, which have a same single frequency and different phases, impinge on an antenna array simultaneously at similar angles, a large error occurs in the angle estimation when the phase of two signals is different by 0 or 180 degrees. This phenomenon might occurs for low-flying target since direct signals and surface-reflected signals are on the same range bin because of relatively small bandwidth of shipborne radar. In this paper, we show the Cramer-Rao lower bound of the angle estimation lowered by using multiple frequencies. Also, using maximum likelihood estimation, we show that mean square error of the angle estimation lowered when we use multi-frequency radar.