Abstract: The optimum difference pattern can be synthesized rigorously. The method make use of theZolotarev polynomials, and is analogous to the Dolph-Chebyshev synthesis of the optimum sum patterns.However, the implementation of the method is not trivial. This paper presents a new synthesis method by taking advantage of the properties of the optimum difference patterns. Being a numerical iteration algorithm, the newmethod is simple to implement, and is versatile to use, and can achieve the precision required by engineering.