Abstract: An analysis technique----quasi-TEM wave analysis for gap discontinuity insuspended stripline is proposed. On either side of the discontinuity, the gap discontinuities with the same structure are inserted at equal spacing so that periodic discontinuity arrangement is constructed. The periodic length is so chosen that the interactions beween adjacent discotinuities vanish. A periodic range of them is analyzed. Its total capacitance is calculated by the two-dimensional Fourier transformation technique, from which the equivalent parameters of the discontinuity is obtained. when the suspended stripline degenerates into the stripline, numerical results are in agreement with the given by R. S. Yahya, et al. (1974).