Computer simulation of the cavity geometry for a S-band side coupled cavity

In recent year, the computer codes for solving 3-D full-wave electromagnetic field, for example CST (microwave studio) or HFSS (high frequency structure simulation), just have enough accurate to used for the multi-cavities accelerating structure design, such as dispersion relation, cavity geometry, et.al.. Before that, the geometry design was just based on analytical expression, experimental trial test and designer´s experience. Due to non-linearity and complication, it is very difficult to determine the geometry of cavities or structure without computer simulation code. This paper technically describes the calculation method of the cavity geometry by CST code[1].