Open-ended Coaxial Cavities with Corrugated Inner and Outer Walls

In this work an open-ended coaxial cavity with a corrugated insert and a relatively small number of corrugations on the outer wall is studied. In particular, the Spatial Harmonics Method (SHM) is employed in order to derive the TE modes characteristic equation, which is then solved by truncation for the calculation of the corresponding eigenvalues. Special care is given in the expansion functions used in order to avoid numerical instabilities in the calculation of high-order spatial terms. Various cases of outer wall corrugations are studied numerically in order to identify the effect of the outer corrugations and understand the mode coupling mechanism.