Abstract: This paper describes the sum and difference patterns of monopulse linear arrays of equally spaced discrete inphase elements which are excited in such a way that the envelope of the excitation amplitudes is uniform, triangular, or V in shape. Analysis of the radiation patterns is carried out by using exact or truncated Z-transform, and then the compact form as S （z） = F（z） - G （z）, i. e. Eq. （ 4 ）, is obtained. This method was first developed by D. K. Cheng and M. T. Ma in 1960. With the aid of Eq. （ 8 ） or the formula of G （z） derived from the shifting theorem, S （z） can be found simply by the unilateral Z-transform without considering whether the envelope function is symmetrical or unsymmetrical. Also a numerical example is given, showing that the theoretically calculated sum pattern compares quite favorably with that obtained from experiments, especially in the major region the test data and the analytical results have been found in fairly satisfactory agreement. The difference pattern also has been checked by experiments. The method proposed here is simple and easy to carry out.