This paper deals with the measurement error of elevation angle for low-altitude target tracking with monopulse radars in the presence of multipath

which degrades the target tracking algorithms greatly.By means of the theoretical analysis and computer simulation based on real environment

we confirm that the fixed bias compensation can't solve some real

scenarios'

problem.Then we develop a novel compensation technique after the estimate of phase difference between direct and reflective path.Also

we can use it as a threshold to eliminate the peak error in the tracking stage.Complex monopulse ratio is utilized and the accuracy of tracking is improved

especially in some kinds of

scenarios

.