Abstract: The analog or digital phase shifters without dispersion characteristics will cause the antenna beam direction change with the frequency, viz. , the aperture effect of the phased array antenna. In engineering the instantaneous bandwidth of phased array antenna can be expanded by using the real-time delay line with dispersion characteristics at the subarray level, but the delay quantification error at the subarray level will produce periodic grating lobe, which will lead to the deterioration of the performance of the antenna sidelobe. In this paper, it is proposed that the small bit delay line be set on the channel (or multi-channel T/ R unit) and superimposed with large bit delay line at the subarray level, to eliminate or improve the delay error at the subarray level. In this paper, combined with X-band active two-dimensional array antenna, three cases of element level, subarray level and subarray+element level are simulated. The simulation results show that the subarray+element two-stage delay method can obviously improve the sidelobe characteristics of the phased array antenna while expanding the instantaneous bandwidth of the phased array antenna, and the method has a strong engineering feasibility.