Analysis and design of sum and difference directivity functions for the DBF in subarray

DBF in subarray finds important application in modern radar. In this paper we analyze two types of the sum and difference directivity functions of the DBF in subarray. We deduce the condition for the formation of grating lobes and discuss directivity functions in both cases of ideal channel and of channel mismatch. We present a kind of modified methods which improve the conventional weighting methods for suppressing sidelobe. These methods modify weighting coefficients according to the relative positions of the subarrays in array. And they are adaptable for array structure and are suitable for the DBF in subarray. Both of the analyses and the simulation results demonstrate that presented methods are effective.