Analysis of an edge slot waveguide antenna using a combined finite element and moment methods

Abstract

A numerical analysis method for analyzing radiation characteristic of an edge slot waveguide antenna by using combined finite element and moment methods is presented in this thesis. The finite element method has been used to find the approximate solution of the electric field in the cavity of the slot in order to incorporate the wall thickness of slot into the numerical modeling. As the finite element method is less efficient than the moment method for the case of open region, the moment method is employed in free space outside the slot cavity which includes region in rectangular waveguide and free space region outside the radiation slot. Thus, the combined finite element method and moment method has been proposed in this thesis in order to combined the merit of both methods. In addition, the concept of using singular element has been firstly investigated in this thesis for improving the accuracy of approximation of electric field at the corners of the edge slot. The numerical examples have been carried out to validate the program written by the author. The computed results of electric field distribution along the slot and resonant length agree well with other published results. The proposed method has been employed to find other parameters which are useful for designing antenna such as normalized conductance versus slot inclination angle and radiation patterns. By investigating the use of singular element, it is found that the singular element cannot be used in this case of combined finite element and moment method because of the conflict nature of interpolation functions using in finite element and moment methods.