Most of present spatial spectrum estimation methods is only suitable for the situation that the digital output of all array elements must be known

namely the methods based on element level.2-D spatial spectrum estimation methods at subarray level applied to phased array radar are studied.Applying the method based on simplified array manifold only needs to determine the phase center and gain of each subarray accurately and thus can reduce array calibration cost and expense greatly.However the available direction estimation region is only within the 3dB beam width of subarrays

in order to estimate at any interested direction one can combine this method with beam scanning.Post-processing the subarray outputs by introducing weighting network makes the array processing more flexible.The method based on simplified array manifold with the ideal subarray patterns is constructed which can overcome the limitation of the one based on direct simplified array manifold that the available region of direction estimation can’t be adjusted and suppress sidelobe sources better.Simulation results demonstrate the validity of the proposed methods.