Dispersion Diagrams of Linear Slow-Wave Structures

Analytically calculated dispersion diagram of an over-moded nine-periods V-band slow-wave structure (SWS) designed to operate in a slow- or surface-wave TM
03
mode is re-examined using two-dimensional Poisson SuperFish code allowing to precisely cal-culate electric field spatial patterns of all azimuthally-symmetric transverse-magnetic (TM) modes possible to exist in this SWS. It is shown that the analytically calculated dispersion curves of higher-order TM
0n
modes of the SWS are not the dispersion curves of pure TM
0n
modes, but fascinating combinations of themselves with dis-persion curves of all lower-order TM
0(n-k)
modes, where k= 1 … (n-1). Such, for example, an analytically calculated dispersion curve of TM
03
mode is factually a combination of three different dispersion curves: (i) one of the TM
031
mode with 1=0 … 4, (ii) another one of the TM
011
mode with 1=5 … 7, and (iii) third one of the TM
021
mode with 1=8 … 9, where I is an axial index of axial TM
0n1
modes.