Design procedure for longitudinal slot arrays fed by air-filled rectangular waveguide including mutual coupling has been discussed and studied in many papers, and widely applied.Due tocomplexity of internal field, it is difficult toemploy the same method on slot arrays fed by ridge waveguide. In this paper, a newdesign procedureis introduced for slot arrays fed by single-ridge waveguide, which simplified the procedure of the previous one.A array wasconstructed and tested, and the result validates the theory.