HFSS(High Frequency Structure Simulator) was used to calculate the S parameter of the different structural microwave chemistry reactor made of rectangular waveguide resonator

while changing the structure dimension of the microwave chemistry reactor such as shape and dimensions of iris

diameter of reaction tube and thickness of reaction tube wall

material and positions of reaction tube.The optimal simulating results were consistent with experimental results and the optimal structure dimensions of the microwave chemistry reactor were given.The positions of the reaction tube and the plunger affected the distribution of electromagnetic field in microwave chemistry reactor

and hence it directly affected the work of the microwave chemistry reactor.In the optimal structure reactor

where the positions of the reaction tube and the plunger were 106mm and 146mm respectively

the methane in reaction tube were positioned at the strongest and uniform electric intensity

which made it easier for the methane obtain enough microwave power to discharge.The simulating results were consistent with our experimental results.