The altitude of a target can only be estimated roughly by very high frequency(VHF) radar for this kind of radar has a wide beam which is usually be split because of the reflection from the ground.To resolve this problem

the paper proposes an accurate and effective method for measuring the altitude based on beam split

namely

Phase-comparison and Amplitude-comparison.In this measuring system

several antennas of different heights are utilized.Owing to the certain relationship among the phases of the split beams of different antennas

the phases of the echoes can be used to determine the elevation region the targets locate.Using "Amplitude-comparison" of echoes from various antennas to pick up the normalized error signals

the elevation of the target is obtained through looking up the table.An analysis of the effect on the altitude measurement accuracy caused by the roughness of ground is presented.This method has been used in some radar

and has been successfully used in the experiment of the altitude measurement in VHF radar.It has been proved that this approach is effective to measure the altitude of a target which has a rather low elevation.