Particularity in dispersion properties of "closed ring" accelerating structure

Differing from an usual linear biperiodical chain of coupled cells, closed in a ring biperiodical chain allows excitation in dispersion curve for twice less number of types for oscillations. At each type exist two oscillations with the same frequencies. Closing into a ring cancels existing for linear chains prohibition for independent excitation of "p/2-like" mode in coupling cells. Symmetrical position in frequency of neighbor modes requires the same frequencies both for accelerating and coupling cells. This case at operating frequency exist two – "p/2-like" modes – in accelerating cells and in coupling cells. Results of lumped circuit analysis and direct CST simulations are presented