Research On Lumped Port Excitation Sources For Method Of Moments

The analysis of antenna radiation by Mo M has always been a key issue in electromagnetic analysis.Among them,the lumped excitation source has become one of the main antenna excitation sources in Mo M due to its clear definition form,easy loading and easy realization.However,when the lumped excitation source is used to solve the antenna with wave port structure,the antenna input impedance results will appear frequency offset,which is different from the wave port results.To solve these problems,the Matrix Pencil Method is used to improve the solving accuracy of lumped excitation sources,and the reflection coefficient method is used to analyze and solve the antenna radiation problem in different scenes.First of all,this thesis introduces the surface integral equations commonly used in electromagnetic problems in detail,as well as the basic theory of Mo M.Secondly,starting from the Delta-Gap excitation source model,a similar ?-current source is derived,and a Half-RWG excitation source is given.The excitation source model is more consistent with the engineering practice,and has better effect in solving the port parameters of microstrip structure.Then,when the lumped excitation source is used to solve the port parameters of the antenna with wave port structure,the accurate port parameters cannot be obtained due to the reflection of the feed port.In this thesis,the Matrix Pencil Method is used to separate the incident wave and the reflected wave at the port,and the reflection coefficient of the port is solved by using the incident wave and the reflected wave,and then the input impedance of the antenna is solved.Finally,based on the symmetry of excitation source,the antenna radiation problem in different scenes is analyzed.The mirror image principle is introduced,and the antenna model with symmetry is analyzed and solved by using this principle.The reflection coefficient method is used to solve the antenna radiation problem in the dielectric half-space,and extended to the approximate analysis of the antenna in the dielectric plate.The results of numerical examples show that proposed methods are in good agreement with the simulation results of commercial software,which indicates the effectiveness and feasibility of proposed methods.