A calculation means for RF couplers numerical simulation design

The RF coupler is an important component for a Linac accelerating structure. It must be well matched to the feeding waveguide and has synchronous frequency for the proper phase advance in the structure so that the input power is fed into effectively and an excellent travelling wave is transmitted in the accelerating cavities train. In our project, S-Band Linac Radiation Facility R&D, a calculation means for RF coupler numerical simulation design was considered by computing the phase of scattering parameter S11 and the good results are obtained in conjunction with microwave measurement. In this paper, the three-dimension time-domain S-parameters calculation for coupler design is described in detail. The results and analysis of computation and measurement are presented.