Airborne MIMO Radar Space-timadaptive Processing Under Heterogeneous Clutter

The airborne radar has the advantage over the conventional radar due to its owncharacteristics, it is able to detect the airspace and ground targets in the supervisory areaaccurately in time, and search the targets while tracking simultaneously. In the modernwarfare, the airborne radar has become an indispensable tool to compile information ofthe whole battlefield. The complex work environment, diversiform interference,reliability of the equipments and some other technical indicators give much strictrequirements to the airborne radar.The multi-input multi-output (MIMO) radar, as a new type of radar, results fromthe MIMO technique from the area of communication. The MIMO radar transmitsorthogonal signals, which will form into a wide beam with a low gain. Thenmulti-receive beams can be get after the digital beam forming (DBF) to simulate thetransmitted beams. The MIMO radar has some novel characters compared with theconventional radar, when the MIMO technique is used in the airborne radar, it canenhance the ability of targets resolution, weak targets detection, signals anti-interceptionand etc.The background of the study in this thesis is heterogeneous clutter, the cluttercharacteristics of the airborne MIMO radar is analyzed and studied, the STAPprocessing of the clutter spectrum compensation in the nonhomogeneous environmentcaused by the correlation of the clutter and range, and also in the background of theisolated strong clutter, is processed. The main work is as follow:(1) The clutter characteristics of the airborne MIMO radar with differentplacements of the antennas are studied. The nonhomogeneous of the clutter caused bythe correlation of the clutter power spectrum and the range is studied and the clutter dataof different range cells are obtained from the clutter modelling. The data in the cellsneed to be compensated is shifted to the consult cell by angle-Doppler compensation(ADC) to superpose the centre of the clutter spectrums of the cells to enhance the abilityof the clutter cancellation. Use the ADC as the base for further study, the MSAC isemployed to compensate the data after ADC, the spatial frequency is compensated in some Doppler channels. The expandable clutter spectrum can be made thinner and thecancellation ability can be enhanced more.(2) The characteristics of the isolated strong clutter of the airborne MIMO radar areanalyzed. Under the background of the homogenous clutter and multiple isolated targets,the clutter characteristics of the dense and sparse array of the airborne MIMO radar andthe phase array radar are compared. The results show that the strong targets presentsignificantly effect when the direction of the isolated interference is the same with thedetected direction. When the direction is the same, point target interference is containedin the covariance matrix, so a notch will be formed for the processing of the target,which will give a strong cancellation to the target. Eliminate the smallest data and themultiple large data form the received clutter data, and then estimate the covariancematrix.