Abstract: A model of high frequency waveguide line array far-field directivity of the model is calculated based on the with unequal gaps between the waveguides is proposed. The principle of multiplication and the radiation characteristics of in-phase point source array. Then the directivity is further studied by finite element simulation. The calculation is verified by experiment and shows good consistency. By analyzing the directivity of the model, the result shows that the directivity of equal gaps and unequal gaps between the waveguides has almost no difference when the active radiating factor remains unchanged.