The analytical solution to the spaced position and frequency coherence functions of the GNSS type fields propagating through the ionosphere is given. The explicitly constructed coherence functions are obtained for the quadratic structure function of the electron density fluctuations of the ionosphere and the inhomogeneous background ionosphere, where the dependence of the plasma frequency along the line of sight is presented by two half-parabolic layers modelling the topside and bottom side ionosphere with different scales. The solution to the problem is expressed through the appropriate solutions of the equation for the function of the parabolic cylinder.