Analysis of Coupled Space Harmonics in Millimeter-Wave Overmoded Corrugated Structures with Finite and Infinite Length

The coupled space harmonics in a millimeter-wave overmoded corrugated structure with finite- and infinite-length are analyzed. For a comprehensive physics analysis, the electromagnetic modes constructing the coupled space harmonics are studied using simulated two- and three-dimensional field patterns in corrugated and smooth-walled structures with finite length based on electric and magnetic boundary conditions. Simulation results show that specific stopbands will emerge at all of the intersections between the dispersion curves of different TM0n, modes when considering infinite-length structures with corrugations. The number of split coupled harmonics with finite length will be increased. The dispersion relations of finite length structures are thus regrouped according to the stopbands and become the same shape as that of the infinite structure which is derived analytically. This provides a significant basis to clarify the electromagnetic characteristics for transferring the dispersion relations of finite length structures into infinite structures.