Coupling Loss (C.L.) is a key parameter for designing the Leaky Waveguide (LWG) Antennas. In this paper, a new method for analyzing and optimization of LWG antennas to obtain a desired Coupling Loss is presented. This is done by optimizing the spacing between slots using piecewise uniform slot spacing scheme. The Method of Moments (MoM) and Spectrum of Two Dimensional Solutions technique (S2DS) are combined to achieve a fast and accurate method for calculating the unknown distribution of the electric field in the slots. These fields are then used to find the radiation pattern and C.L. of the antenna. Excitation fields at the slots are evaluated by considering the mutual couplings between slots. To maintain the C.L along the antenna within a given desired level, an optimization scheme is employed to adjust the slot spacing such that the propagation loss along the antenna is compensated.