Three-coordinate phased array radar detects aerial targets such as unmanned aerial vehicles and helicopters. The flight of each type of target generally has its typical height, and will not exceed a fixed height. Based on the general scheme design of radar system and the typical characteristics of radar target distribution in pitch dimension, a refined design method for detecting airspace and waveform is presented, which may effectively shorten the radar searching time and improve the radar searching. This method can also be used in the design of detection waveforms for ground targets.