The Shanghai Synchrotron Radiation Facility (SSRF) adopts a 2998 MHz linac
which is in similar structure of the SLAC linac
but the dimensions are slightly different
hence the need of calculating the coupler dimensions.This paper focused on the simulation of the coupler.The simulation used three–frequency mode just like testing the accelerator in the laboratory.The physics design of 2998 MHz coupler was carried out using the Superfish code with two-dimensional finite difference method
and the HFSS code with the three-dimensional finite element method.The simulation result is greatly agreement with the experiment test.