Bilateral approach for the dispersion characteristic of waves over the open comb

Closure equation, witch takes into account both the dispersion and amplitude properties in both regions of open comb, was obtained. On the basis of the closure equation the bilateral approximations were theoretically justified for the eigen waves of open comb. Regularities for the numbers of accountable space harmonics, using the system of certain order for oscillations in resonators, were found for bilateral approximations to obtain the lowest average error. Bilateral approximations are correct for the comb with the combs of finite thickness. Accuracy of calculation has an order of magnitude higher, than the one with the same order has without bilateral approximations.