In this paper, a sparse array with increasing spacing is proposed to construct a fourth-order different co-array (FODCA) for direction of arrival (DOA) estimation. Being different from the conventional sparse arrays, the spacing of adjacent sensors gradually increases according to an arithmetic sequence. The element spacing between the two closest sensors is many times the half-wavelength of the incident signal. Hence, the proposed array can reduce the mutual coupling effect more effectively than many other types of sparse arrays. Some simulation results can prove the effectiveness of the proposed array.