A study on angle estimation by maximum likelihood method for low elevation radar tracking

摘要

In monopulse tracking radar, angle error for low elevation target are brought out by multipath of sea surface refraction. Even if the direction of arrival for direct signal have been obtained, accurate target position could not be derived on account of gradient of refractivity in low layer atmosphere. In this paper, we present maximum likelihood estimation of two-path specula refraction model considering effective earth-radius factor by an array antenna. Following results are obtained by computer simulation in case for sea specula refraction. * The phase difference of each radiating element for arriving signals should be considered. * Almost true value is estimated in case for two parameter search for the effective earth-radius factor and the target height. * The argument of Fresnel refraction efficiency has been considered as -180 degrees. * In the case that effective radius of the earth is not standard atmosphere, the bias error about 5m has been generated by maximum likelihood estimation in assumption of standard atmosphere.