Antenna beam-null arrangement based on time-direction pattern by knowledge-aided method

In traditional adaptive nulling antennae, the beam-nulls come into being perfectly for stationary jamming signals. But their ability of nulling will be severely weakened for nonstationary jamming signals so that the target detection performance becomes worse for radar. In this paper the new conception of time-direction pattern for radars is introduced, in which the information for direction change with time is obtained by direction finding for all spatial signals continuously. Under the inferential rules given by the knowledge, the nonstationary jamming signals are discerned, and their directions of arrival can be deduced by histogram projection and statistic process for the time-direction pattern. Then the fixed beam-nulls are arranged for those jamming directions according to above result. The adaptive nulling is next used for the other jamming leavings. In this way, all kinds of jamming signals in space can be eliminated greatly. Simulation results are given to support the validity of our scheme.