The extraction method for direct path wave in the airborne passive radar system

In the passive radar system, it does not transmit the electromagnetic wave signal by itself. So it is the most important to get pure direct path wave received together with the ground clutter as reference signal. For suppressing the clutter, we can make the receiving array rotate a certain angle in certain situation to decrease the receiving beam-width in the elevation coordinate. Firstly, we calculate the antenna pattern of the receiving array whose elements are in any space position. Than the formula of the receiving beam-width in the radar elevation coordinate is deduced. Finally, the improved method which is helpful to suppress the ground clutter is verified by simulation.