  We present numerical procedures for analyzing the properties of periodic
structures and associated couplers based upon time domain simulation. Simple
post processing procedures are given for determining Brillouin diagrams and
complex field distributions of the traveling wave solutions, and the reflection
coefficient of the traveling waves by the input and output. The availability of
the reflection coefficient information facilitates a systematic and efficient
procedure for matching the input and output. The method has been extensively
applied to coupler design for a wide variety of structures and to a study
directed towards elimination of the surface field enhancement commonly
experienced in coupler cells.
